fill in the rest of the GL functions. finally

libobs-d3d11/d3d11-exports.h

libobs-d3d11/d3d11-subsystem.cpp

libobs-opengl/gl-exports.h

libobs-opengl/gl-helpers.h

libobs-opengl/gl-indexbuffer.c

libobs-opengl/gl-shader.c

libobs-opengl/gl-subsystem.c

libobs-opengl/gl-subsystem.h

libobs-opengl/gl-windows.c

libobs/graphics/graphics-internal.h

libobs/graphics/graphics.c

libobs/graphics/graphics.h