Fix AArch64 linker testsuite failures trigeered by differences in build environments.

	PR 29843
	* testsuite/ld-aarch64/bti-plt-5.d: Relax regxps slightly to allow
	for differences in build environments.
	* testsuite/ld-aarch64/tls-relax-gdesc-le-now.d: Likewise.