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/version.c b/src/version.c
index d024265..86a074b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -672,11 +672,7 @@
 #else
 	"-toolbar",
 #endif
-#ifdef FEAT_USR_CMDS
 	"+user_commands",
-#else
-	"-user_commands",
-#endif
 #ifdef FEAT_VARTABS
 	"+vartabs",
 #else
@@ -772,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1210,
+/**/
     1209,
 /**/
     1208,