Make GC_MAKE_GCPROS_NOOPS the default (Bug#9926).

Make GC_MAKE_GCPROS_NOOPS the default (Bug#9926).

* lisp.h (GC_MARK_STACK): Default to GC_MAKE_GCPROS_NOOPS.
* s/cygwin.h, s/darwin.h, s/freebsd.h, s/gnu.h, s/irix6-5.h, s/msdos.h:
* s/netbsd.h, s/sol2-6.h:
Remove definition of GC_MARK_STACK, since the default now works.
* s/aix4-2.h, s/hpux10-20.h, s/unixware.h:
Define GC_MARK_STACK to GC_USE_GCPROS_AS_BEFORE, since that's
no longer the default.
* s/gnu-linux.h (GC_MARK_STACK): Adjust to change in default.