patch 9.1.0151: ml_get_buf_len() does not consider text properties

Problem:  ml_get_buf_len() does not consider text properties
          (zeertzj)
Solution: Store text length excluding text properties length
          in addition in the memline

related #14123
closes: #14133

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/edit.c b/src/edit.c
index 5760b06..d7c80ff 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -5070,6 +5070,7 @@
 			vim_free(curbuf->b_ml.ml_line_ptr);
 		    curbuf->b_ml.ml_line_ptr = newp;
 		    curbuf->b_ml.ml_line_len -= i;
+		    curbuf->b_ml.ml_line_textlen = (int)STRLEN(newp) + 1;
 		    curbuf->b_ml.ml_flags =
 			   (curbuf->b_ml.ml_flags | ML_LINE_DIRTY) & ~ML_EMPTY;
 		}