#10 Patch for make test_version for lusers

[Ian Abbott]

This applies to the standalone build of the serial
module.

The Makefile (or rather the 'make' program) runs
test_version.sh which uses depmod to check for
unresolved symbols. test_version.sh only does this if
'which depmod' succeeds.

As depmod is usually installed in /sbin or /usr/sbin
and this is often not in the ordinary user's PATH (e.g.
a stock RedHat system), this part of test_version.sh
will not do its job when make is run by an ordinary
user.

This patch just forces /sbin and /usr/sbin into the
PATH when the Makefile runs test_version.sh.

[Ian Abbott]

Patch Makefile to force /sbin and /usr/sbin into PATH when running test_version.sh