Backport from master

Backport from master

2023-04-11  Michael Meissner  <meissner@linux.ibm.com>

gcc/

	PR target/109067
	* config/rs6000/rs6000.c (create_complex_muldiv): Delete.
	(init_float128_ieee): Delete code to switch complex multiply and divide
	for long double.  Backport from master, 3/20/2023.
	(complex_multiply_builtin_code): New helper function.
	(complex_divide_builtin_code): Likewise.
	(rs6000_mangle_decl_assembler_name): Add support for mangling the name
	of complex 128-bit multiply and divide built-in functions.

gcc/testsuite/

	PR target/109067
	* gcc.target/powerpc/divic3-1.c: New test.  Backport from master,
	3/20/2023.
	* gcc.target/powerpc/divic3-2.c: Likewise.
	* gcc.target/powerpc/mulic3-1.c: Likewise.
	* gcc.target/powerpc/mulic3-2.c: Likewise.