AX_C_IFDEF

[Peter Johansson]

Hello,

_AC_C_IFDEF
http://www.nongnu.org/autoconf-archive/_ac_c_ifdef.html
seems replaced with AX_C_IFDEF, but I cannot find the latter in the 
documentation.

Anyway, checking the sources I noticed that this functionality is 
available in AC_CHECK_DECL
http://www.gnu.org/software/autoconf/manual/autoconf.html#Generic-Declarations
so I would suggest this macro could be deprecated.

thanks,
Peter