As pointed out by Johannes Sixt and Alexander Gavrilov, commit
2958228430b63f2e38c55519d1f98d8d6d9e23f3 ("gitk: Fix switch statement
in parseviewargs") exposed a latent bug in that $notflag was never
initialized.  Since it isn't used either, this removes it entirely.
Signed-off-by: Paul Mackerras <paulus@samba.org>
                set nextisval 1
                lappend glflags $arg
            }
-           "--not" {
-               set notflag [expr {!$notflag}]
-               lappend revargs $arg
-           }
-           "--all" {
+           "--not" - "--all" {
                lappend revargs $arg
            }
            "--merge" {