PATCH: Use diff -u in fixincludes/check.tpl

[Ralf Wildenhues]

* Rainer Orth wrote on Tue, Mar 02, 2010 at 09:31:14PM CET:
> While looking at the output of make check in fixincludes, I noticed that
> it is in context diff format by default.  I think the unidiff format is
> easier to read and generally preferred by the GCC project, therefore I'd
> like to propose the following patch.

diff -u is not portable, however.

Cheers,
Ralf