Getting rid of .dSYM/ directories

So the new --work-properly option for this is to use -gstabs rather than plain old -g.

For Xcode projects, it looks like there's a choice of setting DEBUG_INFORMATION_FORMAT to one of stabs, dwarf or dwarf-with-dsym (where the last of these is apparently the default), but as far as I can tell the Xcode settings don't affect the proper way of doing things (the command line).