Introduce a new format_type_extended, with a flags bitmask argument that
can modify the default behavior.  A few compatibility and readability
wrappers remain:
	format_type_be
	format_type_be_qualified
	format_type_with_typemod
while format_type_with_typemod_qualified, which had a single caller, is
removed.

Author: Michael Paquier, some revisions by me
Discussion: 20180213035107.GA2915@paquier.xyz