With AM_PROG_AR may report "error: possibly underfined macro: AM_PROG_AR" (mingw, autoreconf-2.68).
Without AM_PROG_AR may report warning "archiver requires 'AM_PROG_AR' in 'configure.ac'" (cygwin, automake-1.12).
They do not affect the tests and install

2, Verifies the EnumValueDscriptor for DynamicMessage.Builder#setField

Increase the allocated_size_ should be after allocation. Otherwise there might have segmentation fault if allocation throws an exception.

"unary minus operator applied to unsigned type, result still unsigned"

https://codereview.appspot.com/86030044/

Replace TSan API declarations in atomicops_internals_tsan.h with a header inclusion (patch from glider@)

Both gcc and clang defines the __aarch64__ macro when building
for the 64-bit AArch64 execution state of ARMv8 processors, so
use this to detect the architecture.