libgfortran: Avoid using libquadmath APIs on powerpc64le on glibc 2.32+

On a glibc 2.32+ build, we still use some libquadmath APIs
when we shouldn't:
readelf -Wr /home/jakub/gcc/obj/powerpc64le-unknown-linux-gnu/libgfortran/.libs/libgfortran.so.5 | grep QUADMATH
00000000002502c8  0000002600000015 R_PPC64_JMP_SLOT       0000000000000000 fmaq@QUADMATH_1.0 + 0
00000000002505f8  0000006700000015 R_PPC64_JMP_SLOT       0000000000000000 tanq@QUADMATH_1.0 + 0
0000000000250930  0000009b00000015 R_PPC64_JMP_SLOT       0000000000000000 fabsq@QUADMATH_1.0 + 0
0000000000250940  0000009d00000015 R_PPC64_JMP_SLOT       0000000000000000 sinq@QUADMATH_1.0 + 0
0000000000250c98  000000cf00000015 R_PPC64_JMP_SLOT       0000000000000000 copysignq@QUADMATH_1.0 + 0
0000000000251038  0000010700000015 R_PPC64_JMP_SLOT       0000000000000000 cosq@QUADMATH_1.0 + 0
0000000000251068  0000010a00000015 R_PPC64_JMP_SLOT       0000000000000000 fmodq@QUADMATH_1.0 + 0
These should use __fmaieee128, __tanieee128 etc. instead.

2022-01-07  Jakub Jelinek  <jakub@redhat.com>

	* libgfortran.h (__copysignieee128, __fmaieee128, __fmodieee128):
	Declare.
	* intrinsics/trigd.c (COPYSIGN, FMOD, FABS, FMA, SIN, COS, TAN): If
	POWER_IEEE128 is defined, define these for kind 17 include.
	* intrinsics/trigd_lib.inc (COPYSIGN, FMOD, FABS, FMA, SIN, COS, TAN):
	Don't define if COPYSIGN is already defined.