font-loc "case" bug

[Michael Kleber]

In emacs 21.3.1, C font-lock coloring is disrupted when the
word "case" appears in a comment or in quotes.  For example,
in the following file:

int main() {
  int i /* this is just fine */ = 1;
  int j /* but it miscolors this case */ = 2;
}

the number "2" is colored as a case label, but is colored
correctly if the last word in the comment is changed to "casey".

--Michael Kleber