aarch64: enable mixed-types for aarch64 simdclones

This patch enables the use of mixed-types for simd clones for AArch64, adds
aarch64 as a target_vect_simd_clones and corrects the way the simdlen is chosen
for non-specified simdlen clauses according to the 'Vector Function Application
Binary Interface Specification for AArch64'.

Additionally this patch also restricts combinations of simdlen and
return/argument types that map to vectors larger than 128 bits as we currently
do not have a way to represent these types in a way that is consistent
internally and externally.

gcc/ChangeLog:

	* config/aarch64/aarch64.cc (lane_size): New function.
	(aarch64_simd_clone_compute_vecsize_and_simdlen): Determine simdlen according to NDS rule
	and reject combination of simdlen and types that lead to vectors larger than 128bits.

gcc/testsuite/ChangeLog:

	* lib/target-supports.exp: Add aarch64 targets to vect_simd_clones.
	* c-c++-common/gomp/declare-variant-14.c: Adapt test for aarch64.
	* c-c++-common/gomp/pr60823-1.c: Likewise.
	* c-c++-common/gomp/pr60823-2.c: Likewise.
	* c-c++-common/gomp/pr60823-3.c: Likewise.
	* g++.dg/gomp/attrs-10.C: Likewise.
	* g++.dg/gomp/declare-simd-1.C: Likewise.
	* g++.dg/gomp/declare-simd-3.C: Likewise.
	* g++.dg/gomp/declare-simd-4.C: Likewise.
	* g++.dg/gomp/declare-simd-7.C: Likewise.
	* g++.dg/gomp/declare-simd-8.C: Likewise.
	* g++.dg/gomp/pr88182.C: Likewise.
	* gcc.dg/declare-simd.c: Likewise.
	* gcc.dg/gomp/declare-simd-1.c: Likewise.
	* gcc.dg/gomp/declare-simd-3.c: Likewise.
	* gcc.dg/gomp/pr87887-1.c: Likewise.
	* gcc.dg/gomp/pr87895-1.c: Likewise.
	* gcc.dg/gomp/pr89246-1.c: Likewise.
	* gcc.dg/gomp/pr99542.c: Likewise.
	* gcc.dg/gomp/simd-clones-2.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-1.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-2.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-4.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-5.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-6.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-7.c: Likewise.
	* gcc.dg/vect/vect-simd-clone-8.c: Likewise.
	* gfortran.dg/gomp/declare-simd-2.f90: Likewise.
	* gfortran.dg/gomp/declare-simd-coarray-lib.f90: Likewise.
	* gfortran.dg/gomp/declare-variant-14.f90: Likewise.
	* gfortran.dg/gomp/pr79154-1.f90: Likewise.
	* gfortran.dg/gomp/pr83977.f90: Likewise.

libgomp/ChangeLog:

	* testsuite/libgomp.c/declare-variant-1.c: Adapt test for aarch64.
	* testsuite/libgomp.fortran/declare-simd-1.f90: Likewise.