Fix `getvv` on MacOS X Lion

When passing an executable file as an argument to strings it will
attempt to parse its headers in order to only look for strings in the
"appropriate" sections.  As I don't have direct access to a Lion machine
I have not been able to perform a deep analysis but it appears that on
Lion the "current" version of XCode produces a Mach-O headers that are
incompatible with Lion's "current" version of strings.  By cat:ing the
binary and filtering it through strings the header parsing is bypassed
and all goes well.

Without this patch the following error message is produced:

    strings: object: /usr/local/opt/vala/bin/valac malformed object (unknown load command 17)