Fix crash in tdehwlib if not exists /sys/devices/system/cpu

This resolves Bug 2584

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit f4fb3a8e71)

tdecore/tdehw/tdehardwaredevices.cpp

@@ -3543,6 +3543,7 @@ void TDEHardwareDevices::addCoreSystemDevices() {
 	TQDir d("/sys/devices/system/cpu/");
 	d.setFilter( TQDir::Dirs );
 	const TQFileInfoList *list = d.entryInfoList();
+	if (list) {
 		TQFileInfoListIterator it( *list );
 		TQFileInfo *fi;
 		while ((fi = it.current()) != 0) {
@@ -3559,6 +3560,7 @@ void TDEHardwareDevices::addCoreSystemDevices() {
 			}
 			++it;
 		}
+	}
 
 	// Populate CPU information
 	processModifiedCPUs();