(PSP) add a C reference implementation of the VFPU audio resampler.

asm version still lacks some improvements found in the C version.
Merge pull request #618 from aliaspider/master

(PSP) add a C reference implementation of the VFPU audio resampler.
Add GET_PROC_ADDRESS interface.

Will come in handy later.
Stylistic cleanups in CC resampler.
Remove some old RSound cruft.
Add resampler tests for CC resampler.
Remove passing around video_data inside RGUI.

Makes very little sense to add cruft to the interface
when it also risks using an invalidated video_data ...
Merge pull request #624 from libretro/rgui-cleanup

Remove passing around video_data inside RGUI.
Use abort() in rarch_assert() to make it debuggable.

SIGABRT is nice.
Include limits.h in miscellaneous.h.

Might fix BSD issues.
Also include msvc_compat.h in misc.h.
Add more sophisticated dependency tracking with -MMD.

Avoids full rebuilds when just one header is changed.
(Apple) Build fix
(Menu) RGUI_MAX_SHADERS becomes GFX_MAX_SHADERS
Check presence of avutil/channel_layout.h.

Apparently needed after all.
(menu context) Go through opaque pointers
Move menu_ctx variable over to driver struct
Take out rgui_handle_t dependency in menu_context.c
Move menu_context.c code into driver.c
Add frame function to menu_ctx_driver_t struct