patch 8.1.1210: support for user commands is spread out

Problem:    Support for user commands is spread out. No good reason to make
            user commands optional.
Solution:   Move user command support to usercmd.c.  Always enable the
            user_commands feature.
diff --git a/src/misc2.c b/src/misc2.c
index 5c5c3eb..79fe702 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -1082,10 +1082,8 @@
     ui_remove_balloon();
 # endif
 
-# if defined(FEAT_USR_CMDS)
-    /* Clear user commands (before deleting buffers). */
+    // Clear user commands (before deleting buffers).
     ex_comclear(NULL);
-# endif
 
 # ifdef FEAT_MENU
     /* Clear menus. */
@@ -1130,7 +1128,9 @@
     free_search_patterns();
     free_old_sub();
     free_last_insert();
+# if defined(FEAT_INS_EXPAND)
     free_insexpand_stuff();
+# endif
     free_prev_shellcmd();
     free_regexp_stuff();
     free_tag_stuff();