PR testsuite/23611, PR testsuite/23615
	* obj-c++.dg/bitfield-3.mm: Include standard headers instead of
	writing prototypes of library functions by hand.
	* obj-c++.dg/bitfield-4.mm: Likewise.
	* obj-c++.dg/const-str-4.mm: Likewise.
	* obj-c++.dg/encode-4.mm: Likewise.
	* obj-c++.dg/encode-5.mm: Likewise.
	* obj-c++.dg/encode-6.mm: Likewise.
	* obj-c++.dg/gnu-runtime-3.mm: Likewise.
	* obj-c++.dg/method-10.mm: Likewise.
	* obj-c++.dg/method-17.mm: Likewise.
	* obj-c++.dg/method-19.mm: Likewise.
	* obj-c++.dg/try-catch-2.mm: Likewise.

From-SVN: r105074