pki: Install pki(1) as utility directly in $prefix/bin

ipsec pki is maintained as alias.

src/ipsec/Android.mk

@@ -19,6 +19,7 @@ $(GEN) : PRIVATE_CUSTOM_TOOL = sed \
 	-e "s:@IPSEC_DISTRO@::" \
 	-e "s:@IPSEC_DIR@:$(strongswan_DIR):" \
 	-e "s:@IPSEC_SCRIPT@:ipsec:" \
+	-e "s:@IPSEC_BINDIR@:$(strongswan_DIR):" \
 	-e "s:@IPSEC_SBINDIR@:$(strongswan_SBINDIR):" \
 	-e "s:@IPSEC_CONFDIR@:$(strongswan_CONFDIR):" \
 	-e "s:@IPSEC_PIDDIR@:$(strongswan_PIDDIR):" \