patch 9.0.0247: cannot add padding to virtual text without highlight

Problem:    Cannot add padding to virtual text without highlight.
Solution:   Add the "text_padding_left" argument. (issue #10906)
diff --git a/src/proto/drawline.pro b/src/proto/drawline.pro
index 99163ac..781cdf1 100644
--- a/src/proto/drawline.pro
+++ b/src/proto/drawline.pro
@@ -1,3 +1,4 @@
 /* drawline.c */
+int text_prop_position(win_T *wp, textprop_T *tp, int vcol, int *n_extra, char_u **p_extra, int *n_attr, int *n_attr_skip);
 int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int nochange, int number_only);
 /* vim: set ft=c : */