configure.ac: deduplicate intrinsics test code
* configure.ac (gcry_cv_cc_aarch64_neon_intrinsics) (gcry_cv_cc_aarch64_neon_intrinsics_cflags): Move test source code to new macro GCRY_AARCH64_NEON_INTRINSICS_TEST. (gcry_cv_cc_ppc_altivec, gcry_cv_cc_ppc_altivec_cflags): Move test source code to new macro GCRY_POWERPC_VECTOR_INTRINSICS_TEST.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>