[objective-c/c++, testsuite] Fix stubify tests for -fnext-runtime.

[objective-c/c++, testsuite] Fix stubify tests for -fnext-runtime.

Fixed to work for x86 as well as powerpc (use the final assembler output
instead of the jump rtl which varies between X86 and PPC).  Amended the
options to reflect this change.

gcc/testsuite/

	Backport from mainline.
	2019-06-20  Iain Sandoe  <iain@sandoe.co.uk>

	* obj-c++.dg/stubify-1.mm: Adjust options and scan-asm checks.
	* obj-c++.dg/stubify-2.mm: Likewise.
	* objc.dg/stubify-1.m: Likewise.
	* objc.dg/stubify-2.m: Likewise.

From-SVN: r277800