bug#15728: 24.3.50; cc-mode incorrectly parses particular macro

[Dima Kogan]

I have the following source file:

=========================================================================
int f(void)
{
#define A(b)                                                            \
  int abc ## b;                                                         \
    g()
}
=========================================================================

This indentation is what the latest emacs thinks is correct. Note that
the g() line is indented ahead of the 'int abc' line. This is wrong;
they should have the same indentation. Indeed this is what happens with
emacs23.

In the latest emacs the syntax parser thinks the g() line is
'statement-cont', instead of 'statement'; this is directly related to
the issue. Furthermore, the 'abc ## b' construct is what's confusing the
parser. Removing the '##' makes it parse correctly again.

I'm observing this issue with all emacs24 builds I've tried, with 'emacs
-Q'.