OpenGL interface backports from the Android port

src/CMakeLists.txt

src/Makefile

src/hardware/hw_defs.h

src/hardware/hw_gpu.c

src/hardware/hw_gpu.h

src/hardware/hw_main.c

src/hardware/r_glcommon/r_glcommon.c

src/hardware/r_glcommon/r_glcommon.h

src/hardware/r_opengl/r_opengl.c

src/hardware/r_opengl/r_opengl.h

src/hardware/shaders/gl_shaders.c

src/hardware/shaders/gl_shaders.h

src/hardware/shaders/shaders_gl2.h

src/hardware/shaders/shaders_gles2.h

src/hardware/shaders/shaders_software.h

src/sdl/Makefile.cfg

src/sdl/hwsym_sdl.c

src/sdl/i_video.c

src/sdl/ogl_sdl.c