unposted: add 'static' to shinsavestack

(cherry picked from commit 309d899507)

ChangeLog

@@ -1,5 +1,8 @@
 2022-01-27  dana  <dana@dana.is>
 
+	* Jun-ichi Takimoto: unposted: Src/input.c: add 'static' to
+	shinsavestack
+
 	* Peter Stephenson: 49290: Src/init.c, Src/input.c: Replace
 	stdio for buffered shell input to avoid memory management
 	interacting with signal handlers.

Src/input.c

@@ -150,7 +150,7 @@ struct shinsaveentry {
 };
 
 /* SHIN buffer save stack */
-struct shinsaveentry *shinsavestack;
+static struct shinsaveentry *shinsavestack;
 
 /* Reset the input buffer for SHIN, discarding any pending input */