st/mesa: Destroy buffer object's mutex.
st/mesa: Destroy buffer object's mutex.

Ideally we should have a _mesa_cleanup_buffer_object function in
src/mesa/bufferobj.c so that the destruction logic resided in a single
place.

Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler