libcoap: update to v4.1.2

Update libcoap to latest stable version 4.1.2
While at it switch from tar extension bz2 to xz

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

libs/libcoap/Makefile

@@ -8,14 +8,15 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libcoap
-PKG_RELEASE:=4
+PKG_VERSION:=v4.1.2
+PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://github.com/obgm/libcoap
 PKG_SOURCE_SUBDIR:=$(PKG_NAME)
-PKG_SOURCE_VERSION:=2da31de732c0e51a9bc9e1d4aea21e25da89cf87
-PKG_SOURCE:=$(PKG_NAME)-$(PKG_SOURCE_VERSION).tar.bz2
-PKG_MIRROR_HASH:=b61fe3245a329dfcf198187149d2072509b18ca6e348d0b423c0f44d11e930e4
+PKG_SOURCE_VERSION:=fa5248603049ddf95cc84608aad569120763bf2b
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
+PKG_MIRROR_HASH:=0ab4bc9569a78904743cc3074fd1c0fc9c78c85fd510fef5145dd872523619e6
 
 PKG_MAINTAINER:=Anton Glukhov <anton.a.glukhov@gmail.com>
 PKG_LICENSE:=GPL-2.0+ BSD-2-Clause