alpha noncompile/940510-1.c segv patch

[Jeffrey A Law]

  In message < 19980102151651.40302@dot.cygnus.com >you write:

  > Given that the code at c-typeck.c:444 is supposed to be supressing
  > further errors from error_marks anyway, a bit of extra checking seems
  > a resonable solution.
[ ... ]

  > Fri Jan  2 15:14:54 1998  Richard Henderson  <rth@cygnus.com>
  > 
  > 	* c-typeck.c (comptypes): Exit early on NULL input.
Thanks.  I've installed this patch.

jeff