aarch64: Skip arm targets in vq*shr*n_high_n intrinsic tests

aarch64: Skip arm targets in vq*shr*n_high_n intrinsic tests

These tests should be skipped for arm targets as the instrinsics
are only supported on aarch64.

gcc/testsuite/ChangeLog

2020-11-10  David Candler  <david.candler@arm.com>

	* gcc.target/aarch64/advsimd-intrinsics/vqrshrn_high_n.c: Added skip
	directive.
	* gcc.target/aarch64/advsimd-intrinsics/vqrshrun_high_n.c: Likewise.
	* gcc.target/aarch64/advsimd-intrinsics/vqshrn_high_n.c: Likewise.
	* gcc.target/aarch64/advsimd-intrinsics/vqshrun_high_n.c: Likewise.