(main): Reflect argument change for dump_setup.
* dump_setup.cc (dump_setup): Add preliminary extra argument for future use.
* path.cc (read_mounts): Open registry with read-only access.
* Makefile.in: Add info for dump_setup.o.
* cygcheck.cc (main): Recognize '-c' option for checking setup installed base.
* path.cc (cygpath): Read mount table if not loaded.