Fix automatic version numbering in the Unix tarball.

Fix automatic version numbering in the Unix tarball.

Manfred Schwarb points out that when I moved the autoconf machinery up
from the unix subdirectory to the top level, in r10141, I missed a
couple of lingering $(srcdir)/.. in the make rule for version.o, as a
result of which the automatic checking of the manifest wasn't doing
its thing and tools built from a standard .tar.gz were reporting as
'Unidentified build'.

[originally from svn r10201]
[r10141 == a947c49bec36957cb5d38e1dc2e22dc0e3465849]