This includes diagnostics for .h files that sprang up when checking a
c file. Those diagnostics are reported to the Flymake infrastructure
which does not (yet) do anything with them.
This includes a change to the test fixtures, too.
* lisp/progmodes/flymake-cc.el (flymake-cc--make-diagnostics): Rework
* test/lisp/progmodes/flymake-resources/another-problematic-file.c:
New file.
* test/lisp/progmodes/flymake-resources/some-problems.h:
Add a function declaration..
