Download source only on remote host

Download source only on remote host

There is no need to download source if we aren't on remote host.
Otherwise, each ld test run on local host leaves behind a couple
test files.

	* config/default.exp (NOPIE_CFLAGS): Download source only on
	remote host.
	(NOPIE_LDFLAGS): Likewise.
	* testsuite/lib/ld-lib.exp (check_lto_available): Likewise.
	(check_lto_fat_available): Likewise.
	(check_lto_shared_available): Likewise.
	(check_ifunc_available): Likewise.
	(check_ifunc_attribute_available): Likewise.