Add support for making fixup_bundle warnings fatal
If I get warnings like e.g.
"warning: target '@rpath/QtSvg.framework/Versions/5/QtSvg' is not absolute..."
they're often indicative of a serious problem (in this case, my macOS DMG is broken because of this).
It would be nice if there was say a FATAL_WARNINGS
parameter to fixup_bundle
, so that my CI can catch things like this without having to parse build output, which is fragile.