[distcc] Fix for FIXME in dcc_trim_path()

[Wayne Davison]

Martin:  any comments on this patch:

    http://www.blorf.net/distcc-fix.patch

It fixes the FIXME in dcc_trim_path() by ensuring that we look for the
executable name that was passed to the invocation of distcc (in the
non-masquerading scenario).  The distccd init still looks for "cc" since
we don't have a specified compiler name at startup time and "cc" is the
most common name to masquerade (I assume).

..wayne..