Re: ld/x86: skip p_align-1 tests with unsuitable compiler

commit d0e0f9c87a3e results "ERROR: i586-linux-cc does not exist" if
cross-building an i586-linux target without a target compiler
installed.

	* testsuite/ld-elf/linux-x86.exp (compiler_honours_aligned): New.
	Use it after first testing check_compiler_available.