gengetopt: add patch to fix compilation warnings in generated code

gengetopt: add patch to fix compilation warnings in generated code

getgetopt generates code that causes compilation warnings in current
versions of gcc. If gengetopt is used for programs that set -Werror during
compilation, these compilation warnings become real problems.

Unfortunately, the gengetopt project seems dead for several years now. Last
release dates back to 2012. There is an open bug for this problem [1], with
a proposed patch, but no response from the maintainers.

Apply the patch from the bug report to fix the problem.

[1]  http://savannah.gnu.org/bugs/?40243

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>