Includes files generated by each of:
   * autogen.sh
   * configure
   * make

Release objects allocated by InitializeDefaultRepeatedFields()

Fix "warning C4018: '<' : signed/unsigned mismatch" 

Fix a bug that causes DynamicMessage.setField() to not work for repeated enum fields.

Fix descriptor validation logic for packed enum fields.

Explicitly specify pyext/cpp_message.py in py_modules list

enum fields.

Replace links to code.google.com/protobuf with developers.google.com/protocol-buffers

Add support for solaris atomicops

Add check for sched_yield in librt

This patch adds support for atomic operations on Solaris, on any platform.
It makes use of the atomic functions made available in Solaris' atomic.h
header.

In Solaris, sched_yield lives in librt, rather than libc. This patch adds a
check which will link in librt if necessary.

generic atomicops: promote Acquire_Store() and Release_Load() to use SEQ_CST fence

__atomic_store_n() cannot take a memory model argument of
__ATOMIC_ACQUIRE, and __atomic_load_n() cannot take a memory model
argument of __ATOMIC_RELEASE, per the GCC documentation:

    https://gcc.gnu.org/onlinedocs/gcc-4.9.1/gcc/_005f_005fatomic-Builtins.html

On Clang this generates a -Watomic-memory-ordering warning.

Promote the fences in Acquire_Store() and Release_Load() to the stronger
__ATOMIC_SEQ_CST memory model, which ought to be safe.

Note that there are no actual uses of Acquire_Store() or Release_Load()
in protobuf, though.

This follows the TSAN atomicops implementation, which also uses SEQ_CST
fences for these functions.

(Fixes #25.)

platform_macros.h: #undef GOOGLE_PROTOBUF_PLATFORM_ERROR once it's no longer needed