tracebak.c (IS_BAD_PTR): Use IsBadCodePtr on Win32 to check for ptr validity (process must have read access).

2004-10-26  Pascal Obry  <obry@gnat.com>

	* tracebak.c (IS_BAD_PTR): Use IsBadCodePtr on Win32 to check for ptr
	validity (process must have read access). Set to 0 in all other cases.
	(STOP_FRAME): Now check for ptr validity to avoid a segmentation
	violation on Win32.
	(VALID_STACK_FRAME): Check for ptr validity on Win32 to avoid a
	segmentation violation.

From-SVN: r89675