r303188 (by br):
  Add warn flags for GCC 6.1 compiler.
r303190 (by br):
  Add GCC 6.1 warn flags for kernel as well.
r303271 (by br):
  Fix style.
r303438 (by br):
  o Add warn flags required to build modules with GCC 6.1;
  o Sort GCC 4.8 warn flags.
r303453 (by br):
  Normalise the CWARNFLAGS inter-word spacing: remove all leading and
  trailing space, and convert multiple consecutive spaces to single
  space.