The functional_test.sh harness for each test subdir was inspired
by the version in bin/sh/tests/functional_test.sh
Some gymnastics were required to deal with implicit rules for
.c / .o -> .out as the suffix transformation rules were
incorrectly trying to create the test outputs from some of the
source files
Sponsored by: EMC / Isilon Storage Division
The latter is already defined in bsd.libnames.mk, so avoid the conflict
in case someone copy-pastes make variables
While here, switch path to the top of the source tree with SRCTOP