sdk 1.4.0: Patch dhcps_lease structure to let lwIP build.

Based on vendor "patch" at http://bbs.espressif.com/viewtopic.php?f=46&t=1221 .

Makefile

@@ -81,6 +81,7 @@ sdk_patch: .sdk_patch_$(VENDOR_SDK)
 
 .sdk_patch_1.4.0:
 	patch -N -d $(VENDOR_SDK_DIR_1.4.0) -p1 < c_types-c99.patch
+	patch -N -d $(VENDOR_SDK_DIR_1.4.0) -p1 < dhcps_lease.patch
 	@touch $@
 
 .sdk_patch_1.3.0:

dhcps_lease.patch

@@ -0,0 +1,10 @@
+--- esp_sdk/include/user_interface.h.org	2016-01-01 21:22:29.000000000 +0200
++++ esp_sdk/include/user_interface.h	2015-09-22 04:13:52.000000000 +0300
+@@ -275,6 +275,7 @@
+ };
+ 
+ struct dhcps_lease {
++	bool enable;
+ 	struct ip_addr start_ip;
+ 	struct ip_addr end_ip;
+ };