Perf: Use per-thread cache of Calendar objects for calculating zip entry dates
Perf: Use per-thread cache of Calendar objects for calculating zip entry dates

Summary:
JProfiler showed we were creating over 150,000 `Calendar` objects
for each `buck build buck` (about 30 MiB of memory).

While these objects are not thread-safe, it's fine to re-use them as long
as we don't use them across threads.

Since `EntryAccounting` is the only place in Buck that uses `Calendar`s, I
took the easy way out and introduced a `ThreadLocal<Calendar>` cache to
re-use the Calendars.

I also noticed we were not specifying a `Locale` when creating the `Calendar`.
That meant for Buck users in countries like Thailand that don't use the
Gregorian calendar, we were creating invalid ZIP files with years like 2558
instead of 2015.

I fixed this by passing `Locale.US`, since we don't really want to create
ZIP files with localized calendar years.

Test Plan:
`buck build buck`, used JProfiler to confirm many hundreds of
thousands fewer `Calendar` objects created.

Reviewed By: sdwilsh

fb-gh-sync-id: ff9b1eb

darkforestzero/buck,LegNeato/buck,SeleniumHQ/buck,brettwooldridge/buck,robbertvanginkel/buck,dsyang/buck,ilya-klyuchnikov/buck,Dominator008/buck,romanoid/buck,bocon13/buck,vine/buck,justinmuller/buck,kageiit/buck,Distrotech/buck,justinmuller/buck,romanoid/buck,k21/buck,justinmuller/buck,liuyang-li/buck,vine/buck,rowillia/buck,k21/buck,SeleniumHQ/buck,k21/buck,ilya-klyuchnikov/buck,davido/buck,Addepar/buck,OkBuilds/buck,clonetwin26/buck,liuyang-li/buck,illicitonion/buck,davido/buck,daedric/buck,romanoid/buck,daedric/buck,bocon13/buck,Addepar/buck,davido/buck,shybovycha/buck,mikekap/buck,raviagarwal7/buck,LegNeato/buck,robbertvanginkel/buck,Addepar/buck,LegNeato/buck,LegNeato/buck,romanoid/buck,liuyang-li/buck,dsyang/buck,LegNeato/buck,bocon13/buck,janicduplessis/buck,OkBuilds/buck,darkforestzero/buck,dsyang/buck,sdwilsh/buck,brettwooldridge/buck,Distrotech/buck,zpao/buck,bocon13/buck,raviagarwal7/buck,janicduplessis/buck,Dominator008/buck,zhan-xiong/buck,facebook/buck,rowillia/buck,Distrotech/buck,shs96c/buck,vschs007/buck,mikekap/buck,ilya-klyuchnikov/buck,romanoid/buck,bocon13/buck,shybovycha/buck,grumpyjames/buck,sdwilsh/buck,shs96c/buck,rmaz/buck,clonetwin26/buck,zhan-xiong/buck,kageiit/buck,dsyang/buck,sdwilsh/buck,darkforestzero/buck,nguyentruongtho/buck,janicduplessis/buck,daedric/buck,vschs007/buck,mogers/buck,rmaz/buck,rowillia/buck,OkBuilds/buck,daedric/buck,janicduplessis/buck,vschs007/buck,liuyang-li/buck,grumpyjames/buck,mikekap/buck,Dominator008/buck,justinmuller/buck,mogers/buck,zhan-xiong/buck,justinmuller/buck,mogers/buck,davido/buck,clonetwin26/buck,OkBuilds/buck,vine/buck,janicduplessis/buck,robbertvanginkel/buck,mikekap/buck,k21/buck,SeleniumHQ/buck,rowillia/buck,justinmuller/buck,facebook/buck,facebook/buck,darkforestzero/buck,Addepar/buck,mogers/buck,robbertvanginkel/buck,romanoid/buck,liuyang-li/buck,raviagarwal7/buck,OkBuilds/buck,rowillia/buck,darkforestzero/buck,rowillia/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,zpao/buck,zhan-xiong/buck,shs96c/buck,daedric/buck,ilya-klyuchnikov/buck,marcinkwiatkowski/buck,SeleniumHQ/buck,Addepar/buck,mogers/buck,clonetwin26/buck,justinmuller/buck,clonetwin26/buck,zpao/buck,raviagarwal7/buck,davido/buck,romanoid/buck,Distrotech/buck,brettwooldridge/buck,k21/buck,marcinkwiatkowski/buck,rowillia/buck,zhan-xiong/buck,romanoid/buck,vschs007/buck,marcinkwiatkowski/buck,Distrotech/buck,darkforestzero/buck,Addepar/buck,rmaz/buck,facebook/buck,janicduplessis/buck,kageiit/buck,rowillia/buck,bocon13/buck,Dominator008/buck,marcinkwiatkowski/buck,Dominator008/buck,daedric/buck,raviagarwal7/buck,k21/buck,daedric/buck,sdwilsh/buck,sdwilsh/buck,ilya-klyuchnikov/buck,mogers/buck,brettwooldridge/buck,bocon13/buck,nguyentruongtho/buck,liuyang-li/buck,mikekap/buck,Dominator008/buck,rmaz/buck,vschs007/buck,vine/buck,Addepar/buck,k21/buck,davido/buck,zhan-xiong/buck,rmaz/buck,SeleniumHQ/buck,grumpyjames/buck,rmaz/buck,grumpyjames/buck,mikekap/buck,Distrotech/buck,vine/buck,zpao/buck,raviagarwal7/buck,clonetwin26/buck,grumpyjames/buck,sdwilsh/buck,grumpyjames/buck,romanoid/buck,sdwilsh/buck,k21/buck,bocon13/buck,justinmuller/buck,OkBuilds/buck,Addepar/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,brettwooldridge/buck,mogers/buck,rmaz/buck,justinmuller/buck,Dominator008/buck,daedric/buck,SeleniumHQ/buck,robbertvanginkel/buck,shybovycha/buck,shybovycha/buck,zhan-xiong/buck,JoelMarcey/buck,Addepar/buck,nguyentruongtho/buck,illicitonion/buck,ilya-klyuchnikov/buck,LegNeato/buck,rmaz/buck,davido/buck,shybovycha/buck,clonetwin26/buck,zhan-xiong/buck,mikekap/buck,marcinkwiatkowski/buck,shybovycha/buck,OkBuilds/buck,sdwilsh/buck,janicduplessis/buck,LegNeato/buck,mikekap/buck,Dominator008/buck,illicitonion/buck,OkBuilds/buck,davido/buck,shs96c/buck,romanoid/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,Distrotech/buck,robbertvanginkel/buck,nguyentruongtho/buck,liuyang-li/buck,OkBuilds/buck,k21/buck,rmaz/buck,justinmuller/buck,vine/buck,zhan-xiong/buck,robbertvanginkel/buck,daedric/buck,JoelMarcey/buck,kageiit/buck,shs96c/buck,raviagarwal7/buck,sdwilsh/buck,vschs007/buck,mogers/buck,SeleniumHQ/buck,JoelMarcey/buck,LegNeato/buck,mogers/buck,clonetwin26/buck,rowillia/buck,Addepar/buck,mikekap/buck,JoelMarcey/buck,LegNeato/buck,shs96c/buck,raviagarwal7/buck,dsyang/buck,LegNeato/buck,brettwooldridge/buck,k21/buck,k21/buck,dsyang/buck,vschs007/buck,vschs007/buck,bocon13/buck,illicitonion/buck,zpao/buck,bocon13/buck,mikekap/buck,darkforestzero/buck,janicduplessis/buck,zhan-xiong/buck,zpao/buck,OkBuilds/buck,Distrotech/buck,shybovycha/buck,robbertvanginkel/buck,rmaz/buck,JoelMarcey/buck,shs96c/buck,daedric/buck,mikekap/buck,vine/buck,Distrotech/buck,SeleniumHQ/buck,Addepar/buck,Dominator008/buck,vschs007/buck,vschs007/buck,marcinkwiatkowski/buck,grumpyjames/buck,ilya-klyuchnikov/buck,grumpyjames/buck,justinmuller/buck,davido/buck,LegNeato/buck,davido/buck,Dominator008/buck,illicitonion/buck,vschs007/buck,robbertvanginkel/buck,janicduplessis/buck,romanoid/buck,SeleniumHQ/buck,JoelMarcey/buck,marcinkwiatkowski/buck,vine/buck,OkBuilds/buck,zhan-xiong/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,JoelMarcey/buck,liuyang-li/buck,clonetwin26/buck,illicitonion/buck,rmaz/buck,justinmuller/buck,vschs007/buck,ilya-klyuchnikov/buck,dsyang/buck,k21/buck,vine/buck,shs96c/buck,illicitonion/buck,marcinkwiatkowski/buck,liuyang-li/buck,facebook/buck,LegNeato/buck,dsyang/buck,brettwooldridge/buck,clonetwin26/buck,SeleniumHQ/buck,grumpyjames/buck,vine/buck,darkforestzero/buck,brettwooldridge/buck,sdwilsh/buck,dsyang/buck,davido/buck,rowillia/buck,liuyang-li/buck,bocon13/buck,rmaz/buck,davido/buck,clonetwin26/buck,shs96c/buck,k21/buck,vschs007/buck,marcinkwiatkowski/buck,daedric/buck,sdwilsh/buck,rmaz/buck,kageiit/buck,OkBuilds/buck,Distrotech/buck,SeleniumHQ/buck,robbertvanginkel/buck,daedric/buck,grumpyjames/buck,nguyentruongtho/buck,ilya-klyuchnikov/buck,davido/buck,illicitonion/buck,SeleniumHQ/buck,facebook/buck,clonetwin26/buck,darkforestzero/buck,shs96c/buck,OkBuilds/buck,janicduplessis/buck,shybovycha/buck,daedric/buck,JoelMarcey/buck,brettwooldridge/buck,Addepar/buck,dsyang/buck,mogers/buck,illicitonion/buck,dsyang/buck,shs96c/buck,romanoid/buck,nguyentruongtho/buck,JoelMarcey/buck,rowillia/buck,illicitonion/buck,raviagarwal7/buck,raviagarwal7/buck,illicitonion/buck,rowillia/buck,illicitonion/buck,nguyentruongtho/buck,LegNeato/buck,raviagarwal7/buck,darkforestzero/buck,zhan-xiong/buck,robbertvanginkel/buck,marcinkwiatkowski/buck,mikekap/buck,sdwilsh/buck,janicduplessis/buck,sdwilsh/buck,shs96c/buck,robbertvanginkel/buck,brettwooldridge/buck,marcinkwiatkowski/buck,shybovycha/buck,JoelMarcey/buck,facebook/buck,dsyang/buck,marcinkwiatkowski/buck,dsyang/buck,kageiit/buck,illicitonion/buck,raviagarwal7/buck,Dominator008/buck,vine/buck,Dominator008/buck,ilya-klyuchnikov/buck,shybovycha/buck,brettwooldridge/buck,grumpyjames/buck,shs96c/buck,shybovycha/buck,mogers/buck,liuyang-li/buck,brettwooldridge/buck,Addepar/buck,darkforestzero/buck,justinmuller/buck,darkforestzero/buck,raviagarwal7/buck,kageiit/buck,zhan-xiong/buck,janicduplessis/buck,bocon13/buck,grumpyjames/buck,robbertvanginkel/buck,romanoid/buck,Distrotech/buck,zpao/buck,shybovycha/buck,darkforestzero/buck,clonetwin26/buck,shybovycha/buck