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/indent.c b/src/indent.c
index 1087bad..56032fa 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -1609,7 +1609,7 @@
 	{
 	    // Allocate memory for the result: the copied indent, new indent
 	    // and the rest of the line.
-	    line_len = (int)STRLEN(ml_get_curline()) + 1;
+	    line_len = ml_get_curline_len() + 1;
 	    line = alloc(ind_len + line_len);
 	    if (line == NULL)
 		return FALSE;