Manual changes for .cc renaming.

gcc/ChangeLog:

	* Makefile.in: Rename .c names to .cc.
	* config.gcc: Likewise.
	* configure: Regenerate. Likewise.
	* configure.ac: Likewise.
	* gengtype.cc (set_gc_used): Likewise.
	(source_dot_c_frul): Likewise.
	(source_dot_cc_frul): Likewise.
	(struct file_rule_st): Likewise.
	(close_output_files): Likewise.
	* config/avr/t-avr: Use CXXFLAGS_* and CXX_FOR_BUILD.

gcc/ada/ChangeLog:

	* Makefile.rtl: Rename .c names to .cc.
	* gcc-interface/Make-lang.in: Likewise.
	* gcc-interface/Makefile.in: Likewise.

libgcc/ChangeLog:

	* libgcov-driver.c: Rename .c names to .cc.

libcpp/ChangeLog:

	* Makefile.in: Rename .c names to .cc.