src/: Transform do-while into while

list cannot be NULL in the first iteration, so we don't need a do-while.

Just in case it's not obvious: we know it's not NULL in the first
iteration because right above, in line 772, we've already dereferenced
it.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

src/useradd.c

@@ -784,7 +784,7 @@ static int get_groups (char *list)
 	 * each name and look it up. A mix of numerical and string
 	 * values for group identifiers is permitted.
 	 */
-	do {
+	while (NULL != list) {
 		char  *g;
 
 		/*
@@ -832,7 +832,7 @@ static int get_groups (char *list)
 		 */
 		user_groups[ngroups++] = xstrdup (grp->gr_name);
 		gr_free (grp);
-	} while (NULL != list);
+	}
 
 	close_group_files ();
 	unlock_group_files ();

src/usermod.c

@@ -236,7 +236,7 @@ static int get_groups (char *list)
 	 * name and look it up. A mix of numerical and string values for
 	 * group identifiers is permitted.
 	 */
-	do {
+	while (NULL != list) {
 		char  *g;
 
 		/*
@@ -281,7 +281,7 @@ static int get_groups (char *list)
 		 */
 		user_groups[ngroups++] = xstrdup (grp->gr_name);
 		gr_free (grp);
-	} while (NULL != list);
+	}
 
 	user_groups[ngroups] = NULL;