SConstruct : Add `-Wextra` to compilation flags
SConstruct : Add `-Wextra` to compilation flags

johnhaddon/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,hradec/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer