Cleanup crereader fonts initialization.

Don't try to register the two fonts Dingbats.cff and StandardSymL.cff
with crengine because it will reject them anyway. But we cannot simply
remove these two fonts because they are used internally by mupdf to
emulate "builtin" fonts which are mandated by Adobe PDF specification to
be present in every valid implementation.

frontend/document/credocument.lua

@@ -31,9 +31,11 @@ function CreDocument:engineInit()
 		-- we need to initialize the CRE font list
 		local fonts = Font:getFontList()
 		for _k, _v in ipairs(fonts) do
-			local ok, err = pcall(cre.registerFont, Font.fontdir..'/'.._v)
-			if not ok then
-				DEBUG(err)
+			if _v ~= "Dingbats.cff" and _v ~= "StandardSymL.cff" then
+				local ok, err = pcall(cre.registerFont, Font.fontdir..'/'.._v)
+				if not ok then
+					Debug(err)
+				end
 			end
 		end