fix warning not recognized in recent Xcode

Seems the trailing semicolon confuses Xcode 5,
as the setting which has it and the following
one are somewhat misinterpreted. With the
semicolon they're only applied to Debug / Release
configuration but not to the other. Removing
the semicolon fixes that.

I wasn't aware of it in the previous "cleanup" commit, but just
found this by accident when 'weak' warnings didn't show up in 
Debug builds but only in Release builds.