cpplib.h (CPP_N_DFLOAT): New.

	* include/cpplib.h (CPP_N_DFLOAT): New.
	* expr.c (interpret_float_suffix): Identify df, dd, and dl
	suffixes as decimal floating point constants.
	(cpp_classify_number): Disallow hexadecimal DFP constants.

Co-Authored-By: Ben Elliston <bje@au.ibm.com>

From-SVN: r108133