rs6000: Use correct names for some trunc/extend libcalls

rs6000: Use correct names for some trunc/extend libcalls

The libcalls for trunc and extend of a decimal float to a binary float,
and vice versa, do not have "2" in the name, although all other such
conversions do.

	* config/rs6000/rs6000.c (init_float128_ibm): Use the correct names
	for conversions between IFmode and the decimal floating point modes.
	(init_float128_ieee): Use the correct names for conversions between
	KFmode and the decimal floating point modes.

From-SVN: r262753