Fix ftbfs on Fedora 34

error: ordered comparison of pointer with integer zero ('char*' and 'int')

Signed-off-by: François Andriot <francois.andriot@free.fr>
(cherry picked from commit 1136b8150f)

tdesudo/tdesudo.cpp

@@ -205,7 +205,7 @@ TdeSudo::TdeSudo(TQWidget *parent, const char *name,const TQString& icon, const
 		chmod(m_tmpname.ascii(),0644);
 	
 	QCStringList output;
-	while (fgets(buf, 1024, f) > 0)
+	while (fgets(buf, 1024, f) != NULL)
 		output += buf; 
 	if (pclose(f) < 0) {
 		kdError() << k_lineinfo << "Could not run xauth.\n";