patch 8.2.4318: various comment and indent mistakes, returning wrong zero

Problem:    Various comment and indent mistakes, returning wrong zero.
Solution:   Fix the mistakes.  Return NULL instead of FAIL.
diff --git a/src/eval.c b/src/eval.c
index b5ccc4b..7ab05be 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -629,10 +629,10 @@
  */
     static char_u *
 deref_function_name(
-	    char_u **arg,
-	    char_u **tofree,
-	    evalarg_T *evalarg,
-	    int verbose)
+	    char_u	**arg,
+	    char_u	**tofree,
+	    evalarg_T	*evalarg,
+	    int		verbose)
 {
     typval_T	ref;
     char_u	*name = *arg;
@@ -2955,7 +2955,7 @@
 
 /*
  * Handle fourth level expression:
- *	+	number addition
+ *	+	number addition, concatenation of list or blob
  *	-	number subtraction
  *	.	string concatenation (if script version is 1)
  *	..	string concatenation