autoconf AC_FUNC_MKTIME breaks with gcc 4.3

[Adrian Bunk <bunk@stusta.de>]

I just tried compiling the emacs22 package from unstable with gcc 4.3, 
and ran into an issue similar to what Martin described back in
May 2007 for another package in #425544, with the following differences:
- it's not an infinite loop but a one minute hang
  (see the alarm() in conftest.c)
- the build therefore proceeds, but emacs wrongly assumes there's no
  working system mktime()
- Martin said it's "a bug in older versions of autoconf", but as far
  as I can see these older versions include the latest upstream
  version and also the Debian package in unstable

For increased fun, fixing autoconf won't automatically fix all current 
and future packages using AC_FUNC_MKTIME (upstream might use an 
unfixed autoconf version).

It could be harmless (except for a few one minute pauses the emacs build 
seems to work fine, and emacs has some replacement function), but 
someone might want to check how many packages in Debian use 
AC_FUNC_MKTIME and whether some of them might have real problems.

cu
Adrian

BTW: Please Cc me on replies.

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed