groff: fix PERLPATH

There is no PERLPATH, but "${USRBINPATH}/env perl".

(From OE-Core rev: 103d668cece420447c12987119459ebd49c208df)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/groff/groff_1.18.1.4.bb

@@ -32,7 +32,7 @@ do_install_append() {
 	# for target as /usr/bin/perl, so fix it to /usr/bin/perl.
 	for i in afmtodit mmroff; do
 		if [ -f ${D}${bindir}/$i ]; then
-			sed -i -e '1s,#!.*perl,#! ${PERLPATH},' ${D}${bindir}/$i
+			sed -i -e '1s,#!.*perl,#! ${USRBINPATH}/env perl,' ${D}${bindir}/$i
 		fi
 	done