Turn on --enable-gcc-warnings-advisory by default
I've had multiple patches fail due to missing the
--enable-gcc-warnings flag in builds. I've also missed really important problems that these warnings would tell me about.
--enable-gcc-warnings by default is probably not a good choice, because GCC warnings vary quite a lot between versions and
-Werror will cause these new warnings to break builds.
-Werror, there's no harm in enabling all of these warnings by default, and this makes us more likely to notice important warnings. We should do it.
- Make the behavior of
--enable-gcc-warnings-advisorydefault when supported by the compiler
- Add an
--enable-fatal-warningsoption to turn on
--enable-fatal-warningsfor backwards compatibility
- Deprecate or ignore
- Optionally, we could have a
--disable-extra-warningsflag, if there's a case where someone wants to turn off these warnings