ld: Use run_host_cmd_yesno in indirect.exp instead of catch exec

Catch "exec $CC_FOR_TARGET" won't use the gas/ld that we just build,
and in fact run_host_cmd_yesno is a better choice for it.

ld/ChangeLog:

	* testsuite/ld-elf/indirect.exp: use run_host_cmd_yesno
	instead of handwrite catch exec $CC_FOR_TARGET.