Fix building with USE_GLES=1

[orbea]

This will fix building mupen64plus-video-rice with make USE_GLES=1 all on Slackware64-current.

    CXX _obj/OGLTexture.o
../../src/OGLRender.cpp: In member function ‘virtual void OGLRender::Initialize()’:
../../src/OGLRender.cpp:111:18: error: ‘GL_DEPTH_CLAMP_NV’ was not declared in this scope
         glEnable(GL_DEPTH_CLAMP_NV);
                  ^
    CXX _obj/Render.o
Makefile:419: recipe for target '_obj/OGLRender.o' failed
make: *** [_obj/OGLRender.o] Error 1
make: *** Waiting for unfinished jobs....
make: *** wait: No child processes.  Stop.

[richard42]

I just pushed a different fix for this issue; it should build for you now.

[orbea]

Thanks!