patch 9.1.0010: Keymap completion is not available

Problem:  Keymap completion is not available
Solution: Add keymap completion (Doug Kearns)

Add keymap completion to the 'keymap' option, user commands and builtin
completion functions.

closes: #13692

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim.h b/src/vim.h
index 3aa04f5..e41dfef 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -841,6 +841,7 @@
 #define EXPAND_SETTING_SUBTRACT	55
 #define EXPAND_ARGOPT		56
 #define EXPAND_TERMINALOPT	57
+#define EXPAND_KEYMAP		58
 
 // Values for exmode_active (0 is no exmode)
 #define EXMODE_NORMAL		1