util/logging.h: add <unistd.h> for write
util/logging.h: add <unistd.h> for write

Thanks to Tuncer Ayaz for the report.

R=rsc, rsc
CC=re2-dev
http://codereview.appspot.com/5286045

tst2005googlecode/re2,nelhage/re2,lamuguo/re2,dragonkid/re2,nelhage/re2,nelhage/re2,tst2005googlecode/re2,dragonkid/re2,PiRSquared17/re2,nelhage/re2,lamuguo/re2,Distrotech/re2,tst2005googlecode/re2,tst2005googlecode/re2,Distrotech/re2,PiRSquared17/re2,tst2005googlecode/re2,pombreda/re2,lamuguo/re2,zeusdeux/re2,zeusdeux/re2,zeusdeux/re2,pombreda/re2,nelhage/re2,PiRSquared17/re2,zeusdeux/re2,pombreda/re2,PiRSquared17/re2,lamuguo/re2,nelhage/re2,PiRSquared17/re2,pombreda/re2,dragonkid/re2,lamuguo/re2,dragonkid/re2,pombreda/re2,zeusdeux/re2,Distrotech/re2,Distrotech/re2,Distrotech/re2,dragonkid/re2