libwebsockets: Upgrade to latest stable release.

Fairly major bump from 1.7.x to 2.0.2.

Changelog (mostly) available at:
https://github.com/warmcat/libwebsockets/blob/v2.0-stable/changelog

Signed-off-by: Karl Palsson <karlp@etactica.com>

libs/libwebsockets/Makefile

@@ -8,7 +8,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libwebsockets
-PKG_VERSION:=1.7.5
+PKG_VERSION:=2.0.2
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz