Maintain interval ->position fields correctly in update_interval
Also fix some anomalies in the handling of byte positions in regexp-emacs.c This fixes bug #34525. * src/intervals.c (SET_PARENT_POSITION): New macro. (update_interval): When moving to an interval's parent, set that parent's ->position field, to maintain the consistency of the tree. * src/intervals.h (struct interval): Amend the comment describing when ->position is valid. * src/pdumper.c: Update the hash associated with struct interval. * src/regex-emacs.c: (re_match_2_internal): Only invoke POINTER_TO_OFFSET on a known character boundary. Only perform arithmetic on character positions, not on byte positions. Correct the argument to an invocation of UPDATE_SYNTAX_TABLE_FORWARD by adding 1 to it (in case wordend:). * src/syntax.c: (update_syntax_table): Remove the now redundant code that set the ->position field of all parents of the interval found by update_interval.