git: git-difftool(1) is a perl script; move it to the -perl subpkg.

Close #1245

srcpkgs/git/template

@@ -1,7 +1,7 @@
 # Template file for "git"
 pkgname=git
 version=2.3.4
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--with-curl --with-expat --with-tcltk
  ac_cv_fread_reads_directories=no ac_cv_snprintf_returns_bogus=no"
@@ -36,7 +36,7 @@ git-perl_package() {
 	short_desc+=" - perl utilities"
 	pkg_install() {
 		for f in add--interactive archimport cvsexportcommit cvsimport \
-			cvsserver relink send-email; do
+			cvsserver difftool difftool--helper relink send-email; do
 			vmove usr/libexec/git-core/git-${f}
 		done
 		vmove usr/share/perl5