[C++ Patch] Kill -ffriend-injection

[C++ Patch] Kill -ffriend-injection

https://gcc.gnu.org/ml/gcc-patches/2018-05/msg00175.html

	* doc/extend.texi (Deprecated Features): Remove
	-ffriend-injection.
	(Backwards Compatibility): Likewise.
	* doc/invoke.texi (C++ Language Options): Likewise.
	(C++ Dialect Options): Likewise.

	c-family/
	* c.opt (ffriend-injection): Remove functionality, issue warning.

	cp/
	* decl.c (cxx_init_decl_processing): Remove flag_friend_injection.
	* name-lookup.c (do_pushdecl): Likewise.

	testsuite/
	Remove -ffriend-injection.
	* g++.old-deja/g++.jason/scoping15.C: Delete.
	* g++.old-deja/g++.mike/net43.C: Delete.

From-SVN: r259904