Fix FTBFS with clang

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>

tdegtk/tdegtk-theme.cpp

@@ -200,8 +200,9 @@ TQString tdeFindDir(const TQString& suffix, const TQString& file1, const TQStrin
 
 TQString runCommand(const TQString& command) {
 	FILE* p = popen(command.latin1(), "r");
-	if ((p == NULL) || (p < 0))
+	if (p == NULL) {
 		return TQString();
+	}
 	
 	TQString ret;
 	while (!feof(p))