crengine patching shouldn't fail if already applied

When patch is already applied, -N will skip applying it again,
but it will also return error exit code which will break
make fetchthirdparty

Makefile

@@ -141,7 +141,7 @@ fetchthirdparty:
 	# CREngine patch: change child nodes' type face
 	# @TODO replace this dirty hack  24.04 2012 (houqp)
 	cd kpvcrlib/crengine/crengine/src && \
-		patch -N -p0 < ../../../lvrend_node_type_face.patch
+		patch -N -p0 < ../../../lvrend_node_type_face.patch || true
 	unzip mupdf-thirdparty.zip -d mupdf
 	# dirty patch in MuPDF's thirdparty liby for CREngine
 	cd mupdf/thirdparty/jpeg-*/ && \