* gdbtypes.c (gdbtypes_post_init): Change names of decimal float types

	* gdbtypes.c (gdbtypes_post_init): Change names of decimal float types
	to conform to C extension for decimal float.
	* c-lang.c (enum c_primitive_types): Add entries for Decimal Floating
	Point types.
	(enum cplus_primitive_types): Likewise.
	(c_language_arch_info): Add Decimal Floating Point builtin types to
	the primitive_type_vector.
	(cplus_language_arch_info): Likewise.