[objective-c/c++, testsuite, 3/3] Workaround for PR90709.

[objective-c/c++, testsuite, 3/3] Workaround for PR90709.

Use the CF-CFString.h, F-NS*.h proxy headers where needed in the objective-c++
testsuite.  Make minor adjustments to tests as required, providing that those
do not alter the test intent.

2019-06-15  Iain Sandoe  <iain@sandoe.co.uk>

	PR objc/90709
	* obj-c++.dg/proto-lossage-7.mm: Use proxy headers.
	* obj-c++.dg/strings/const-cfstring-2.mm: Likewise.
	* obj-c++.dg/strings/const-cfstring-5.mm: Likewise
	* obj-c++.dg/strings/const-str-12.mm: Likewise.
	* obj-c++.dg/syntax-error-1.mm: Likewise.
	* obj-c++.dg/torture/strings/const-cfstring-1.mm: Likewise.
	* obj-c++.dg/torture/strings/const-str-10.mm: Likewise.
	* obj-c++.dg/torture/strings/const-str-11.mm: Likewise.
	* obj-c++.dg/torture/strings/const-str-9.mm: Likewise.
	* obj-c++.dg/cxx-ivars-3.mm: Skip on later Darwin, where the 10.4 API
	in no longer supported, also on m64 where there's no meaning to it.
	* obj-c++.dg/isa-field-1.mm: Suppress unwanted warning, add comment why.
	* obj-c++.dg/objc-gc-3.mm: Skip for Darwin > 16, the API use is an error
	there.
	* obj-c++.dg/qual-types-1.mm: Prune a spurious l64 warning.
	* obj-c++.dg/stubify-1.mm: Tidy up after better compiler warnings.
	* obj-c++.dg/stubify-2.mm: Likewise.
	* obj-c++.dg/try-catch-1.mm: Likewise.
	* obj-c++.dg/try-catch-3.mm: Likewise.

From-SVN: r272327