Log Message:
Update to 2.63:

GNU Autoconf NEWS - User visible changes.

* Major changes in Autoconf 2.63 (2008-09-09) [stable]
  Released by Eric Blake, based on git versions 2.62.*.

** AC_C_BIGENDIAN does not mistakenly report "universal" for some
   bigendian hosts, a regression introduced with universal binary
   support in 2.62.

** AC_PATH_X now includes /lib64 and /usr/lib64 in its list of default
   library directories.

** AC_USE_SYSTEM_EXTENSIONS no longer conflicts with an external
   AC_DEFINE([__EXTENSIONS__]).  This fixes a regression introduced in
   2.62 when using macros such as AC_AIX that were made obsolete in
   favor of the more portable AC_USE_SYSTEM_EXTENSIONS.

** AC_CHECK_TARGET_TOOLS is usable in the non-cross-compile case.

** Newly obsolete macros
   The following macro has been marked obsolete, since current porting
   targets can safely assume C89 semantics that signal handlers return
   void.  We have no current plans to remove the macro.

     AC_TYPE_SIGNAL

** The macros m4_map and m4_map_sep now ignore any list elements
   consisting of just empty quotes, and m4_map_sep now expands its
   separator.  This fixes a regression in 2.62 when these macros were
   first documented, for the sake of clients expecting the semantics
   that these macros had prior to that time.  The new macros m4_mapall
   and m4_mapall_sep, along with extra quoting of the separator, can
   be used to get the semantics that m4_map_sep had in 2.62.

** Clients of m4_expand, such as AS_HELP_STRING and AT_SETUP, can now
   handle properly quoted but otherwise unbalanced parentheses (for
   some macros, this fixes a regression in 2.62).

** Two new quadrigraphs have been introduced: @{:@ for (, and @:}@ for ),
   allowing the output of unbalanced parentheses in more contexts.

** The following m4sugar macros are new:
   m4_joinall  m4_mapall  m4_mapall_sep  m4_reverse  m4_set_add
   m4_set_add_all  m4_set_contains  m4_set_contents  m4_set_delete
   m4_set_difference  m4_set_dump  m4_set_empty  m4_set_foreach
   m4_set_intersection  m4_set_list  m4_set_listc  m4_set_remove
   m4_set_size  m4_set_union

** The following m4sugar macros now accept multiple arguments, as is the
   case with underlying m4:
   m4_defn  m4_popdef  m4_undefine

** The following m4sugar macros now guarantee linear scaling; they
   previously had linear scaling with m4 1.6 but quadratic scaling
   when using m4 1.4.x.  All macros built on top of these also gain
   the scaling improvements.
   m4_bmatch  m4_bpatsubsts  m4_case  m4_cond  m4_do  m4_dquote_elt
   m4_foreach  m4_join  m4_list_cmp  m4_map  m4_map_sep  m4_max
   m4_min  m4_shiftn

** AT_KEYWORDS once again performs expansion on its argument, such that
   AT_KEYWORDS([m4_if([$1], [], [default])]) no longer complains about
   the possibly unexpanded m4_if [regression introduced in 2.62].

** Config header templates `#undef UNDEFINED /* comment */' do not lead to
   nested comments any more; regression introduced in 2.62.