android-emugl: Fix bitness-conditional modules.

This patch ensures that EmuGL modules are only built when necessary,
with regards to their bitness. I.e. if the build doesn't require
64-bit modules, do not try to build them at all.

Change-Id: I50abdd0e33b88d31a40e0857f8860e88dc869c8a
android/base/sockets/SocketErrors.h: new header.

This patch introduces SocketErrors.h as a new header to ensure
that all socket-related error codes are defined. On Posix systems,
this simply does an #include <errno.h>, but on Windows, this
includes the Winsock header and defines missing error codes
if needed.

This is required to support older Mingw32 toolchain versions,
which we need to experiment with fixing x86 -> x86 translation
on Windows.

Change-Id: Iffd7db654f892cf59990dce4ec5e399d8884b27e
android/looper-base.cpp: Remove unnecessary declarations.

This removes three redundant declarations, which are only problematic
when using an older C++ compiler (e.g. older mingw32 toolchains), which
don't understand that they're exact duplicates of other ones, and
complain loudly about these.

Change-Id: I9211feefd06aea09c9b5ab8194e4c9e9f58d31cb
Merge changes I9211feef,Iffd7db65,I50abdd0e

* changes:
  android/looper-base.cpp: Remove unnecessary declarations.
  android/base/sockets/SocketErrors.h: new header.
  android-emugl: Fix bitness-conditional modules.