uniform3iv method
Implementation
void uniform3iv(UniformLocation location, List<int> v){
  int count = v.length;
  final valuePtr = calloc<Int32>(count);
  valuePtr.asTypedList(count).setAll(0, v);
  gl.glUniform3iv(location.id, count ~/ 3, valuePtr);
  calloc.free(valuePtr);
  checkError('uniform3iv');
}