patch 8.1.1823: command line history code is spread out

Problem:    Command line history code is spread out.
Solution:   Put the code in a new file. (Yegappan Lakshmanan, closes #4779)
            Also graduate the +cmdline_hist feature.
diff --git a/src/version.c b/src/version.c
index 0e1641c..ec53de2 100644
--- a/src/version.c
+++ b/src/version.c
@@ -163,11 +163,7 @@
 #else
 	"-cmdline_compl",
 #endif
-#ifdef FEAT_CMDHIST
 	"+cmdline_hist",
-#else
-	"-cmdline_hist",
-#endif
 #ifdef FEAT_CMDL_INFO
 	"+cmdline_info",
 #else
@@ -774,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1823,
+/**/
     1822,
 /**/
     1821,