Build system refinements.

This patch contains changes to the standalone build system
that are preparing for the ability to build the GPU emulation
libraries directly from sources with it.

This requires several patches to said GPU emulation sources
though.

+ Add support for auto-generated C++ files.
+ Add support for host shared libraries.
+ Cleanup 64-bit build conditionals.
+ Build SDL and SDLmain as their own static libraries.

Change-Id: I88dca965d47432dc6b41428d39869f628632d33d
11 files changed