This patch adds another machine_mode wrapper for modes that are
known to be COMPLEX_MODE_P.  There aren't yet many places that make
use of it, but that might change in future.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* coretypes.h (complex_mode): New type.
	* gdbhooks.py (build_pretty_printer): Handle it.
	* machmode.h (complex_mode): New class.
	(complex_mode::includes_p): New function.
	(is_complex_int_mode): Likewise.
	(is_complex_float_mode): Likewise.
	* genmodes.c (get_mode_class): Handle complex mode classes.
	* function.c (expand_function_end): Use is_complex_int_mode.

gcc/go/
	* go-lang.c (go_langhook_type_for_mode): Use is_complex_float_mode.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r251527