do not use rpath on Darwin

bin/9l

diff --git a/bin/9l b/bin/9l
index c10c11e..3fea275 100755
--- a/bin/9l
+++ b/bin/9l
@@ -161,10 +161,12 @@
 case "$tag" in
 *OpenBSD*)
 	ld=gcc
+	userpath=true
 	extralibs="$extralibs -lutil -lpthread"
 	;;
 *FreeBSD*)
 	ld=gcc
+	userpath=true
 	extralibs="$extralibs -lutil"
 	case "`uname -r`" in
 	[5-9].*)
@@ -174,10 +176,12 @@
 	;;
 *BSD*)
 	ld=gcc
+	userpath=true
 	extralibs="$extralibs -lutil"
 	;;
 *Linux*)
 	ld=gcc
+	userpath=true
 	extralibs="$extralibs -lutil"
 	case "${SYSVERSION:-`uname -r`}" in
 	2.6.*)
@@ -207,8 +211,8 @@
 	exit 1
 esac
 
-case "$ld" in
-gcc)
+case "$userpath" in
+true)
 	for i in "$libsl $@"
 	do
 		case "$i" in