patch 8.2.4832: passing zero instead of NULL to a pointer argument

Problem:    Passing zero instead of NULL to a pointer argument.
Solution:   Use NULL. (closes #10296)
diff --git a/src/getchar.c b/src/getchar.c
index 4caa89e..e208dd1 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -2401,14 +2401,14 @@
 		if (modifier == 0)
 		{
 		    if (put_string_in_typebuf(offset, 4, new_string, len,
-							   NULL, 0, 0) == FAIL)
+							NULL, 0, NULL) == FAIL)
 		    return -1;
 		}
 		else
 		{
 		    tp[2] = modifier;
 		    if (put_string_in_typebuf(offset + 3, 1, new_string, len,
-							   NULL, 0, 0) == FAIL)
+							NULL, 0, NULL) == FAIL)
 		    return -1;
 		}
 		return len;