Make the zygote 64-bit for the x86-64 emulator.

Change-Id: I4ad5d1ef2406e947176c8e180822b25c04fc83f0
Merge "Make the zygote 64-bit for the x86-64 emulator."
Update build system for better Clang behavior on Mac.

Change-Id: I1813954681b670807d7e3faaf6d5f5a769cc5f2e
Merge "Update build system for better Clang behavior on Mac."
Switch to new host prebuilt x86_64-linux-glibc2.11-4.6

Change-Id: I763398d523bf4851a13722f72b12ec69d7a4bb4f
Merge "Switch to new host prebuilt x86_64-linux-glibc2.11-4.6"
auto-merger: merge in from aosp/master