patch 8.1.1343: text properties not adjusted for Visual block mode delete

Problem:    Text properties not adjusted for Visual block mode delete.
Solution:   Call adjust_prop_columns(). (closes #4384)
diff --git a/src/misc1.c b/src/misc1.c
index 5dcf268..f83e807 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -434,8 +434,15 @@
 		saved_cursor.col = (colnr_T)(s - newline);
 	}
 #ifdef FEAT_TEXT_PROP
-	adjust_prop_columns(curwin->w_cursor.lnum, (colnr_T)(p - oldline),
-					     ind_len - (colnr_T)(p - oldline));
+	{
+	    int added = ind_len - (colnr_T)(p - oldline);
+
+	    // When increasing indent this behaves like spaces were inserted at
+	    // the old indent, when decreasing indent it behaves like spaces
+	    // were deleted at the new indent.
+	    adjust_prop_columns(curwin->w_cursor.lnum,
+			(colnr_T)(added > 0 ? (p - oldline) : ind_len), added);
+	}
 #endif
 	retval = TRUE;
     }