[Xcb] Splitting up xcb-util repository

[Arnaud Fontaine]

Hi,

    > I have  rewritten my version of the patch and  fully tested it. It
    > does not  make any assumption other than  executable name being m4
    > or gm4. It should resist  changes for a longer period. It would be
    > nice if someone else could test it.

Yesterday, I tested your patch but  it was not working well, so I digged
into  Autoconf  manual  and found  AC_PATH_PROGS_FEATURE_CHECK[0]  macro
(introduced in  Autoconf 2.62),  so I started  writing a patch  based on
this macro.

I have  attached it to  this email.   I tested it  and it seems  to work
well, e.g. it  checks for m4 then gm4 in  PATH:/usr/gnu/bin and stops on
the first one  it finds supporting -I option (which  is confirmed by the
generated configure script).  Feel free  to pick up the patch you prefer
(either yours or mine).

    > Keep in mind this macro will  be there for decades and may be used
    > on platforms you may not expect (GNU/Hurd, embedded systems ...)

I also  had a look  at m4 on  various OS (including Solaris,  Darwin and
FreeBSD), and apparently only m4  on Solaris does not support -I option,
which  is not  surprising because  POSIX only  requires support  for the
command line options -s, -D, and -U. Thus, I think the name of the macro
is a bit  confusing, so I renamed it  to XORG_M4_WITH_INCLUDE_PATH. Hope
that's ok.

Thanks for your comments and help!

Cheers,
--
Arnaud Fontaine (arnau)

[0] http://www.gnu.org/software/autoconf/manual/autoconf.html#index-AC_005fPATH_005fPROGS_005fFEATURE_005fCHECK-316