The vercmptest script needs to be invoked as a bash script for this to
be valid; the -p operator is interpreted as an argument to look up by
sh. This goes way back to commit 3bf94489, done to solve
http://mailman.archlinux.org/pipermail/pacman-dev/2008-July/007180.html

.

Saw this problem running in a virtual machine where sh is not bash, but
in fact dash:

    user@debian-powerpc:~/projects/pacman$ ./test/util/vercmptest.sh
    src/util/vercmp-p: not found
    src/util/vercmp is src/util/vercmp
    vercmp binary (src/util/vercmp) could not be located

Signed-off-by: Dan McGee <dan@archlinux.org>