dhcp: dhcpcd uses a fixed path for PID files

It always uses RUNDIR and the change to NMRUNDIR was in error.  This
could cause NetworkManager not to be able to kill old dhcpcd processes.

src/Makefile.am

@@ -368,6 +368,7 @@ AM_CPPFLAGS += \
 	-DLOCALSTATEDIR=\"$(localstatedir)\" \
 	-DSBINDIR=\"$(sbindir)\" \
 	-DSYSCONFDIR=\"$(sysconfdir)\" \
+	-DRUNDIR=\"$(rundir)\" \
 	\
 	-DNMCONFDIR=\"$(nmconfdir)\" \
 	-DNMLOCALEDIR=\"$(datadir)/locale\" \

src/dhcp-manager/nm-dhcp-dhcpcd.c

@@ -103,7 +103,10 @@ ip4_start (NMDHCPClient *client,
 
 	iface = nm_dhcp_client_get_iface (client);
 
-	priv->pid_file = g_strdup_printf (NMSTATEDIR "/dhcpcd-%s.pid", iface);
+	/* dhcpcd does not allow custom pidfiles; the pidfile is always
+	 * RUNDIR "dhcpcd-<ifname>.pid".
+	 */
+	priv->pid_file = g_strdup_printf (RUNDIR "/dhcpcd-%s.pid", iface);
 
 	if (!g_file_test (priv->path, G_FILE_TEST_EXISTS)) {
 		nm_log_warn (LOGD_DHCP4, "%s does not exist.", priv->path);