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

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

These tests were broken in the first place, and more broken following
the change to drop pic symbol stubs unless the linker needs them.

Fixed to work for x86 as well as powerpc and amended the options to
force pic symbol stubs on.

gcc/testsuite/

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: r272518