[AArch64] Limit simd-abi-9.c function body test to LP64

[AArch64] Limit simd-abi-9.c function body test to LP64

On ILP32 targets, there's an extra UXTW instruction to extend
the incoming pointer before the load.  It doesn't seem worth
complicating the test for that, since all we're checking is
that an optimisation takes place, and that optimisation isn't
related to pointer size.

2019-10-08  Richard Sandiford  <richard.sandiford@arm.com>

gcc/testsuite/
	* gcc.target/aarch64/torture/simd-abi-9.c: Require LP64 for
	the function body test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@276688 138bc75d-0d04-0410-961f-82ee72b054a4