localedata: Do not generate output if warnings were present.

With LC_MONETARY parsing fixed we can now generate locales
without forcing output with '-c'.

Removing '-c' from localedef invocation is the equivalent of
using -Werror for localedef.  The glibc locale sources should
always be clean and free from warnings.

We remove '-c' from both test locale generation and the targets
used for installing locales e.g. install-locale-archive, and
install-locale-files.

Tested on x86_64 and i686 without regressions.
Tested with install-locale-archive target.
Tested with install-locale-files target.

Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 1c7a3456)