Public sources get added to dependencies of the target as well which can
cause duplicate symbols.

This should fix Bazel builds, since those were missing a new file
(implicit_weak_message.cc).

- Removed the redefination in the atomicword_compat.h. Now Atomic32 will
alwyas be intptr_t in 32bit platforms, the bridge is no longer needed.
- Change NaCl 64bit to use intptr_t instead of int32 for Atomic32,
otherwise AtmoicWord APIs will miss the definations.

After this change, the AtmoicWord will always be either Atomic32 or
Atmoic64 depending on the platforms.

Add brief documentation describing each warning suppression.

In protobuf-module.cmake: in addition to checking for release or debug
variants of protoc's location we should also check the configuration "noconfig".

VS2017 warns about a few additional things, for example, files that
define no symbols (which is typically the result of a platform specific
ifdef not applying on Windows).

Suppress these warnings so the build is clean on VS2017.

Adds pkg-config (`.pc`) files for CMake based installs.

Adds pkg-config (`.pc`) files for CMake based installs.

Add implementations of open(2), mkdir(2), stat(2),
etc. that support long paths under Windows (paths
longer than MAX_PATH in <windows.h>, which is 260
characters).

The implementations are in a separate namespace
(google::protobuf::internal::win32), so they won't
collide with the standard implementations in
<io.h>, but after importing them with `using` they
can be drop-in replacements.

Fixes https://github.com/bazelbuild/bazel/issues/2634
Fixes https://github.com/google/protobuf/issues/2891

install 'generated_message_table_driven.h' and 'metadata_lite.h', they are included when compiling the files generated using protoc.exe 3.3.0

tested only on windows with visual studio 2015 as generator

Unfortunate typo. Just one extra ',' symbol, has led to the hidden implicit behavior.

Now everything will be fine.

This allows the file path to contain spaces which is very common on
windows.