patch 9.1.0172: More code can use ml_get_buf_len() instead of STRLEN()

Problem:  More code can use ml_get_buf_len() instead of STRLEN().
Solution: Change more STRLEN() calls to ml_get_buf_len().  Also do not
          set ml_line_textlen in ml_replace_len() if "has_props" is set,
          because "len_arg" also includes the size of text properties in
          that case. (zeertzjq)

closes: #14183

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/mbyte.c b/src/mbyte.c
index d6d81c4..d6fb7ec 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -4378,7 +4378,7 @@
     if (lp->col > 0 || lp->coladd > 1)
     {
 	p = ml_get_buf(buf, lp->lnum, FALSE);
-	if (*p == NUL || (int)STRLEN(p) < lp->col)
+	if (*p == NUL || ml_get_buf_len(buf, lp->lnum) < lp->col)
 	    lp->col = 0;
 	else
 	    lp->col -= (*mb_head_off)(p, p + lp->col);