* Get rid of the RCS Header stuff.  They're meaningless in git.
 * Add public domain comment to some of the files if the only comment
   was the RCS header.

.indent.pro.

lisp.c into the correct <foo>-os.h files.

* backtrace.c, save.c:  fprintf warnings.
* interrupt.h: Declare build_fake_control_stack_frame and
  interrupt_handle_space_overflow.
* os-common.c: Include interrupt.h to define
  build_fake_control_stack_frame.
* parse.c, runprog.c, search.c:  Include some standard system headers
  to get rid of undefined function warnings.

of no utility and wasn't even being maintained thoroughly. Can now use
pseudo atomic in C code. All interrupt contexts are saved, even those
that occur when running foreign C code; this may be necessary for
reliable stack parsing on some operating systems, e.g. Linux.

When the pending interrupt from a GC trigger is processed by
interrupt_handle_pending, any other accumulated pending interrupt is
also processed even if *interrupts-enabled* is false, breaking the
behaviour of the *interrupts-enabled* flag.  The best way around this
for the x86 port is to call maybe-gc directly from the allocation
routines; remove the recently introduced function set_maybe_gc_pending
which also had other problems. Note this problem will likely occur on
the other ports.

GC when it reaches its trigger within pseudo atomic so that maybe_gc
is called at the end of pseudo atomic.

sigcontext.  Hence interrupt_maybe_gc need to take them as arguments.