Thread: port/ build fix

This trivial patch fixes a missing dependency in src/port/Makefile: if
"make install" is run without the "all" target having been previously
built, the build fails. Per report from Kris Jurka.

Barring any objections I'll apply this to HEAD before the end of the
day.

-Neil

Neil Conway wrote:
> This trivial patch fixes a missing dependency in src/port/Makefile: if
> "make install" is run without the "all" target having been previously
> built, the build fails. Per report from Kris Jurka.

Applied.

-Neil