patch 9.1.0821: 'findexpr' completion doesn't set v:fname to cmdline argument

Problem:  'findexpr' completion doesn't set v:fname to cmdline argument.
Solution: Set v:fname to the cmdline argument as-is (zeertzjq).

closes: #15934

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim.h b/src/vim.h
index 74e6b95..f4acaf9 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -845,6 +845,7 @@
 #define EXPAND_KEYMAP		58
 #define EXPAND_DIRS_IN_CDPATH	59
 #define EXPAND_SHELLCMDLINE	60
+#define EXPAND_FINDEXPR		61
 
 
 // Values for exmode_active (0 is no exmode)
@@ -2188,7 +2189,8 @@
 #define VV_TYPE_TYPEALIAS 107
 #define VV_TYPE_ENUM	  108
 #define VV_TYPE_ENUMVALUE 109
-#define VV_LEN		110	// number of v: vars
+#define VV_CMDCOMPLETE	110
+#define VV_LEN		111	// number of v: vars
 
 // used for v_number in VAR_BOOL and VAR_SPECIAL
 #define VVAL_FALSE	0L	// VAR_BOOL