Avoid validating freshly mapped memory.
Avoid validating freshly mapped memory.

Move validation of supposedly zeroed pages from chunk_alloc() to
chunk_recycle().  There is little point to validating newly mapped
memory returned by chunk_alloc_mmap(), and memory that comes from sbrk()
is explicitly zeroed, so there is little risk to assuming that
chunk_alloc_dss() actually does the zeroing properly.

This relaxation of validation can make a big difference to application
startup time and overall system usage on platforms that use jemalloc as
the system allocator (namely FreeBSD).

Submitted by Ian Lepore <ian@FreeBSD.org>.

VRToxin/android_external_jemalloc,vashstorm/jemalloc,android-ia/platform_external_jemalloc,cpeterso/jemalloc,wfxiang08/jemalloc,flyfeifan/jemalloc,wespelee/jemalloc,wqfish/jemalloc,glandium/jemalloc,geekboxzone/mmallow_external_jemalloc,lilothar/jemalloc,geekboxzone/lollipop_external_jemalloc,ahmetmircik/jemalloc,awreece/jemalloc,Dmitry-Me/jemalloc,leebaok/jemalloc-4.2.1-readcode,wqfish/jemalloc,lilothar/jemalloc,kmiku7/jemalloc,xin3liang/platform_external_jemalloc,ahmetmircik/jemalloc,wespelee/jemalloc,leebaok/jemalloc-4.2.1-readcode,CMRemix/android_external_jemalloc,lvfeng1130/jemalloc,cpeterso/jemalloc,geekboxzone/lollipop_external_jemalloc,tempbottle/jemalloc,geekboxzone/mmallow_external_jemalloc,shekkbuilder/jemalloc,lilothar/jemalloc,sudosurootdev/external_jemalloc,shekkbuilder/jemalloc,lvfeng1130/jemalloc,cpeterso/jemalloc,dxq-git/jemalloc,jemalloc/jemalloc-cmake,wfxiang08/jemalloc,percona/jemalloc-debian,vashstorm/jemalloc,wqfish/jemalloc,8l/jemalloc,VRToxin/android_external_jemalloc,CyanogenMod/android_external_jemalloc,AndroidExternal/jemalloc,AndroidExternal/jemalloc,flyfeifan/jemalloc,geekboxzone/lollipop_external_jemalloc,CMRemix/android_external_jemalloc,Snaipe/jemalloc,lvfeng1130/jemalloc,kmiku7/jemalloc,kmiku7/jemalloc,awreece/jemalloc,kmiku7/jemalloc,yy-nm/jemalloc,wfxiang08/jemalloc,xin3liang/platform_external_jemalloc,awreece/jemalloc,tempbottle/jemalloc,xin3liang/platform_external_jemalloc,wqfish/jemalloc,ahmetmircik/jemalloc,TeamExodus/external_jemalloc,garoose/jemalloc,glandium/jemalloc,8l/jemalloc,sudosurootdev/external_jemalloc,awreece/jemalloc,shekkbuilder/jemalloc,flyfeifan/jemalloc,android-ia/platform_external_jemalloc,wespelee/jemalloc,leebaok/jemalloc-4.2.1-readcode,CMRemix/android_external_jemalloc,dxq-git/jemalloc,TeamExodus/external_jemalloc,Snaipe/jemalloc,android-ia/platform_external_jemalloc,CyanogenMod/android_external_jemalloc,8l/jemalloc,shekkbuilder/jemalloc,lilothar/jemalloc,garoose/jemalloc,garoose/jemalloc,flyfeifan/jemalloc,jemalloc/jemalloc-cmake,vashstorm/jemalloc,garoose/jemalloc,android-ia/platform_external_jemalloc,sudosurootdev/external_jemalloc,CyanogenMod/android_external_jemalloc,geekboxzone/mmallow_external_jemalloc,leebaok/jemalloc-4.2.1-readcode,xin3liang/platform_external_jemalloc,wqfish/jemalloc,yy-nm/jemalloc,Snaipe/jemalloc,VRToxin/android_external_jemalloc,vashstorm/jemalloc,CMRemix/android_external_jemalloc,dxq-git/jemalloc,jemalloc/jemalloc-cmake,VRToxin/android_external_jemalloc,wespelee/jemalloc,CyanogenMod/android_external_jemalloc,geekboxzone/lollipop_external_jemalloc,geekboxzone/mmallow_external_jemalloc,Dmitry-Me/jemalloc,Snaipe/jemalloc,percona/jemalloc-debian,percona/jemalloc-debian,dxq-git/jemalloc,AndroidExternal/jemalloc,8l/jemalloc,yy-nm/jemalloc,sudosurootdev/external_jemalloc,TeamExodus/external_jemalloc,Dmitry-Me/jemalloc,tempbottle/jemalloc,cpeterso/jemalloc,glandium/jemalloc,glandium/jemalloc,percona/jemalloc-debian,TeamExodus/external_jemalloc,lvfeng1130/jemalloc,ahmetmircik/jemalloc,tempbottle/jemalloc,yy-nm/jemalloc,wfxiang08/jemalloc,Dmitry-Me/jemalloc,AndroidExternal/jemalloc,jemalloc/jemalloc-cmake