only do libpam on apple

Summary: Doing what paravoid suggested on https://github.com/facebook/hhvm/pull/2085

Reviewed By: @fredemmott

Differential Revision: D1412431
use system sqlite if present

Summary: porting from http://anonscm.debian.org/gitweb/?p=collab-maint/hhvm.git;a=tree;f=debian/patches;h=d3f6359591ab2af99d1f8ce24bc37a7cb5353aac;hb=HEAD

Reviewed By: @fredemmott

Differential Revision: D1412602
use system double-conversion if present

Summary: upstreaming commit from http://anonscm.debian.org/gitweb/?p=collab-maint/hhvm.git;a=tree;f=debian/patches;h=d3f6359591ab2af99d1f8ce24bc37a7cb5353aac;hb=HEAD

Reviewed By: @fredemmott

Differential Revision: D1412494
use system liblz4 if available

Summary: Upstreaming http://anonscm.debian.org/gitweb/?p=collab-maint/hhvm.git;a=blob;f=debian/patches/use_system_lz4;h=efdaae12088122a7ff7baa0fd6cf03b5f194df7b;hb=HEAD

Reviewed By: @fredemmott

Differential Revision: D1412662
use libzip on the system if present

Summary: Upstreaming from http://anonscm.debian.org/gitweb/?p=collab-maint/hhvm.git;a=blob;f=debian/patches/use_system_libzip;h=07c87fc685dab67d6dfc4b0c1851f1f78249e3a1;hb=HEAD

Reviewed By: @fredemmott

Differential Revision: D1413045