Log Message:
databases/percona-toolkit: Remove ${WRKDIR} references in scripts.

Several Perl-generated scripts were installed with the interpreter
being in the tools directory.  Use subst.mk to fix the interpreter
path at the head of these scripts.  Add "sh" as a run-time tool
dependency since several of the scripts installed require a POSIX
shell.

Bump the PKGREVISION due to changes in the installed scripts.