Remove unecessary and broken MC/DC compile test

The __sigsetjmp test was added as a regression test in an early
iteration of the MC/DC support, as it caused an internal compiler error.
This was triggered by a code path which did not make it through to the
final revision.  Since this test really only worked on systems with
__sigsetjmp, and does not serve a purpose any more it can be removed.

gcc/testsuite/ChangeLog:

	* gcc.misc-tests/gcov-19.c: Remove test.

gcc/testsuite/gcc.misc-tests/gcov-19.c

@@ -869,17 +869,6 @@ dest:
     goto * 0;
 }
 
-int __sigsetjmp ();
-
-/* This should compile, but not called. */
-void
-mcdc021c ()
-{
-  while (x) /* conditions(0/2) true(0) false(0)*/
-	    /* conditions(end) */
-     __sigsetjmp ();
-}
-
 /* If edges are not properly contracted the a && id (b) will be interpreted as
    two independent expressions. */
 void