Set the clock to 0 before reading application link files

0 is the default clock value, which doesn't get written to link files
if it's not changed. The clock was previously uninitialised before
reading link files, so it would get written with a random value if
there was none before.

src/linkapp.cpp

@@ -93,6 +93,8 @@ LinkApp::LinkApp(GMenu2X *gmenu2x_, const char* linkfile)
 	file = linkfile;
 #ifdef ENABLE_CPUFREQ
 	setClock(gmenu2x->getDefaultAppClock());
+#else
+	setClock(0);
 #endif
 	selectordir = "";
 	selectorfilter = "*";