Disable --long-plt test for arm-nacl targets.

ld/testsuite/
	* ld-arm/arm-elf.exp (armelftests_common): Move long-plt case ...
	(armelftests_nonacl): ... here.
Apply ld-arm/gc-hidden-1 to all ELF targets, not just *eabi* targets

ld/testsuite/
	* ld-arm/gc-hidden-1.d: Remove target, add not-target to match
	other ELF-only tests in this directory.  Loosen regexps so they
	don't care what the exact addresses are.