libwebsockets

ignore leading spaces when checking for a suitable subprotocol

My Browsers send as Subprotocols e.g. chat, superchat, mySubprotocol (with spaces after the ,). Libwebsockets now checked if ' mySubprotocol' was equal to 'mySubprotocol' which failed. With this fix the leading space is ignored and uses 'mySubprotocol' for comparision.