[ARM] Fix, add tests for FP16 aapcs.

[ARM] Fix, add tests for FP16 aapcs.

testsuite/
	* gcc.target/arm/aapcs/neon-vect10.c: Require
	-mfloat-ab=hard.  Replace arm_neon_fp16_ok with arm_neon_fp16_hw.
	* gcc.target/arm/aapcs/neon-vect9.c: Likewise.
	* gcc.target/arm/aapcs/vfp18.c: Likewise.
	* gcc.target/arm/aapcs/vfp19.c: Likewise.
	* gcc.target/arm/aapcs/vfp20.c: Likewise.
	* gcc.target/arm/aapcs/vfp21.c: Likewise.
	* gcc.target/arm/fp16-aapcs-1.c: Require
	-mfloat-ab=hard.  Also simplify the test.
	* gcc.target/arm/fp16-aapcs-2.c: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237849 138bc75d-0d04-0410-961f-82ee72b054a4