build: add emoji.css

without it jami-client-gnome won't build

Change-Id: Ife26e5820a20740f6972bb70346e14e0489d6ba0

CMakeLists.txt

@@ -384,6 +384,7 @@ SET(libringclient_WEB_chatview
    src/web-chatview/chatview.js
    src/web-chatview/jed.js
    src/web-chatview/emoji.js
+   src/web-chatview/emoji.css
    src/web-chatview/linkify-html.js
    src/web-chatview/linkify-string.js
    src/web-chatview/linkify.js