disable mouse handler before executing ext cmd

Otherwise we get crashes.

src/command.c

@@ -2987,7 +2987,7 @@ static void perform_external_cmd(int call, int lh, char *ext_cmd)
     char *lh_d;
 
     if (mouse_en)
-      mouse_hide();
+      mouse_disable();
 #if SYNC_ENV
     /* the below is disabled because it seems we don't need
      * to update our copy of env. djgpp creates the env segment
@@ -3095,10 +3095,7 @@ static void perform_external_cmd(int call, int lh, char *ext_cmd)
     reset_text_attrs();
     gppconio_init();  /* video mode could change */
     if (mouse_en)
-      {
-      mouse_reset();
-      mouse_show();
-      }
+      mouse_enable();
 
     sprintf(el, "%d", error_level);
     setenv("ERRORLEVEL", el, 1);

src/ms.c

@@ -203,7 +203,7 @@ int mouse_init(void)
     return 1;
 }
 
-void mouse_reset(void)
+void mouse_enable(void)
 {
     __dpmi_regs r = { };
 
@@ -212,9 +212,11 @@ void mouse_reset(void)
     r.x.es = newm.segment;
     r.x.dx = newm.offset16;
     __dpmi_int(0x33, &r);
+
+    mouse_show();
 }
 
-void mouse_done(void)
+void mouse_disable(void)
 {
     __dpmi_regs r = { };
 
@@ -225,6 +227,11 @@ void mouse_done(void)
     r.x.es = oldm.segment;
     r.x.dx = oldm.offset16;
     __dpmi_int(0x33, &r);
+}
+
+void mouse_done(void)
+{
+    mouse_disable();
     __dpmi_free_real_mode_callback(&newm);
     __dpmi_free_memory(mregs.handle);
 }

src/ms.h

@@ -2,7 +2,8 @@
 #define MS_H
 
 int mouse_init(void);
-void mouse_reset(void);
+void mouse_enable(void);
+void mouse_disable(void);
 void mouse_done(void);
 void mouse_show(void);
 void mouse_hide(void);