rs6000.c (TARGET_MANGLE_DECL_ASSEMBLER_NAME): Define as rs6000_mangle_decl_assembler_name.

[gcc]
2018-10-24  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (TARGET_MANGLE_DECL_ASSEMBLER_NAME):
	Define as rs6000_mangle_decl_assembler_name.
	(rs6000_mangle_decl_assembler_name): If the user switched from IBM
	long double to IEEE long double, switch the names of the long
	double built-in functions to be <func>f128 instead of <func>l.

[gcc/testsuite]
2018-10-24  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/float128-math.c: New test to make sure the
	long double built-in function names use the f128 form if the user
	switched from IBM long double to IEEE long double.
	* gcc.target/powerpc/ppc-fortran/ieee128-math.f90: Likewise.

From-SVN: r265471