m4: add Werror when checking for compiler flags

Seemingly that at some point clang started accepting _any_ flags,
whereas previously it would error out.

These days, you can give it -Whamsandwich and it will succeed, while
at the same time throwing an annoying warning.

Add -Werror so that everything gets flagged and set accordingly.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108082
Cc: Vinson Lee <[email protected]>
Repored-by: Vinson Lee <[email protected]>
Signed-off-by: Emil Velikov <[email protected]>
Reviewed-by: Dylan Baker <[email protected]>
Reviewed-by: Eric Engestrom <[email protected]>

0 files changed, 0 insertions, 0 deletions