code: func GetSubroutineUniformLocation(program uint32, shadertype uint32, name *uint8) int32 {
  	ret, _, _ := syscall.Syscall(gpGetSubroutineUniformLocation, 3, uintptr(program), uintptr(shadertype), uintptr(unsafe.Pointer(name)))
  	return (int32)(ret)
  }
docs: // retrieve the location of a subroutine uniform of a given shader stage within a program