patch 9.1.0770: current command line completion is a bit limited

Problem:  current command completion is a bit limited
Solution: Add the shellcmdline completion type and getmdcomplpat()
          function (Ruslan Russkikh).

closes: #15823

Signed-off-by: Ruslan Russkikh <dvrussk@yandex.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim.h b/src/vim.h
index ebca6ae..387fe4f 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -844,6 +844,7 @@
 #define EXPAND_TERMINALOPT	57
 #define EXPAND_KEYMAP		58
 #define EXPAND_DIRS_IN_CDPATH	59
+#define EXPAND_SHELLCMDLINE	60
 
 
 // Values for exmode_active (0 is no exmode)