Ruby implementation Map#inspect should be consistent with Hash#inspect

Properly support maps in Ruby protoc and another bugfix.

Previously, we supported map fields in the Ruby DSL. However, we never
connected the final link in the chain and generated `map` DSL commands
for map fields in `.proto` files. My apologies -- I had been testing
with the DSL directly so I missed this.

Also fixed a handlerdata-setup-infinite-loop when a map value field's
type is its containing message.

MIPS: remove immediate constraint within CompareAndSwap.

Add java compiled targets and several tests target into .gitignore.

Improper use of immediate constraint is slightly non-optimal with gcc/gnu-as
but may cause breakage with clang.

Add missing LIBPROTOC_EXPORT to ruby generator

Updated to latest upb and added test for JSON map operation.

add #to_ary to RepeatedField

MSVC protoc compiler fix

Support oneofs in MRI Ruby C extension.

<stdint.h> is not part of the standard, so I've added a workaround.

https://github.com/google/protobuf/issues/87

Fix illegal C++ use of reinterpret_cast<> to cast between nullptr_t and a pointer

- A golden-file test that ensures protoc produces known-valid output.
- A Ruby test that loads that golden file and ensures it actually works
  with the extension.

This split strategy allows us to test end-to-end without needing to
integrate the Ruby gem build system and the protoc build system. This is
desirable because we do not want a gem build/install to depend on
building protoc, and we do not want building protoc to depend on
building and testing the gem.

Support for maps in the MRI C Ruby extension.

Include names.h as java_names.h in the opensource tree