Remove ml_ prefix from cursor.h functions

s/ml_get_curline/get_cursor_line_ptr
s/ml_get_cursor/get_cursor_pos_ptr

src/nvim/quickfix.c

@@ -1639,7 +1639,7 @@ win_found:
            * found, reduce the error column value by the length of
            * a tab character.
            */
-          line = ml_get_curline();
+          line = get_cursor_line_ptr();
           screen_col = 0;
           for (char_col = 0; char_col < curwin->w_cursor.col; ++char_col) {
             if (*line == NUL)