Convert debug_printf to take UTF-8 strings instead of wchar_t.

This fixes the problem where passing a non-ASCII string to
debug_printf(L"%hs", s) caused vswprintf_s to fail on Linux (because it
doesn't know what encoding the char* is meant to have). Now debug
messages will remain as UTF-8 until they reach the OS.

Fixes #3021.

This was SVN commit r16332.

source/scriptinterface/ScriptInterface.cpp

@@ -150,7 +150,7 @@ bool print(JSContext* cx, uint argc, jsval* vp)
 		std::wstring str;
 		if (!ScriptInterface::FromJSVal(cx, args[i], str))
 			return false;
-		debug_printf(L"%ls", str.c_str());
+		debug_printf("%s", utf8_from_wstring(str).c_str());
 	}
 	fflush(stdout);
 	args.rval().setUndefined();