glcpp/tests: Update 063-comments.c.expected to match output.

The expected result has been out of sync with what glcpp produces for
some time; glcpp's actual result seems to be correct and is very close to
GCC's cpp.  Updating this will make it easier to catch regressions in
upcoming commits.

src/glsl/glcpp/tests/063-comments.c.expected

@@ -5,8 +5,15 @@ f = g /h;
  l();
 m = n
 + p;
+
+
+
+
+
+
  
 more code here
+
  
 are not treated like comments.