[libcpp] struct deps renaming

https://gcc.gnu.org/ml/gcc-patches/2019-05/msg00199.html
	libcpp/
	* include/mkdeps.h: Rename struct deps to struct mkdeps.
	* mkdeps.c: Likewise.
	* include/cpplib.h (cpp_get_deps): Rename return type..
	* directives.c (cpp_get_deps): Likewise.
	* internal.h (struct cpp_reader): Rename deps field type.

	gcc/c-family/
	* c-opts.c (handle_defered_opts): Rename struct deps to struc mkdeps.

From-SVN: r270905