genmodes: Define NUM_MODE_* macros

genmodes: Define NUM_MODE_* macros

I was working on a patch that needed to calculate the number of
modes in a particular class.  It seemed better to have genmodes
generate this directly rather than do the kind of dance that
expmed.h had.

gcc/
	* genmodes.c (emit_insn_modes_h): Define NUM_MODE_* macros.
	* expmed.h (NUM_MODE_INT): Delete in favor of genmodes definitions.
	(NUM_MODE_PARTIAL_INT, NUM_MODE_VECTOR_INT): Likewise.
	* real.h (real_format_for_mode): Use NUM_MODE_FLOAT and
	NUM_MODE_DECIMAL_FLOAT.
	(REAL_MODE_FORMAT): Likewise.