patch 8.2.3976: FEARG_LAST is never used

Problem:    FEARG_LAST is never used. (Dominique Pellé)
Solution:   Remove FEARG_LAST and the related code.

src/evalfunc.c

@@ -1202,7 +1202,6 @@ typedef struct
 #define FEARG_2    2	    // base is the second argument
 #define FEARG_3    3	    // base is the third argument
 #define FEARG_4    4	    // base is the fourth argument
-#define FEARG_LAST 9	    // base is the last argument
 
 #ifdef FEAT_FLOAT
 # define FLOAT_FUNC(name) name
@@ -2718,14 +2717,7 @@ call_internal_method(
     if (argcount + 1 > global_functions[fi].f_max_argc)
 	return FCERR_TOOMANY;
 
-    if (global_functions[fi].f_argtype == FEARG_LAST)
-    {
-	// base value goes last
-	for (i = 0; i < argcount; ++i)
-	    argv[i] = argvars[i];
-	argv[argcount] = *basetv;
-    }
-    else if (global_functions[fi].f_argtype == FEARG_2)
+    if (global_functions[fi].f_argtype == FEARG_2)
     {
 	// base value goes second
 	argv[0] = argvars[0];

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3976,
 /**/
     3975,
 /**/