autoconf 2.62 failure due to AS_VAR_IF

[Gerald Pfeifer]

On Tue, 18 May 2010, Gerald Pfeifer wrote:
> Using autoconf 2.62 on my primary test system I am getting:
> 
>   configure:26081: error: possibly undefined macro: AS_VAR_IF
> 
> Indeed use of AS_VAR_IF appears relatively new, and it seems this may be 
> similar to AS_VAR_APPEND where we have the following in configure.ac:
> 
>   dnl autoconf versions before 2.63b don't have AS_VAR_APPEND
>   m4_ifdef([AS_VAR_APPEND],,[as_fn_append () { eval $[1]=\$$[1]\$[2]; }
>   AC_DEFUN([AS_VAR_APPEND],[as_fn_append $1 $2])])dnl
> 
> I assume we need something similar here, too?  I am really far from
> an autoconf hacker -- is this something one of you could look into?

Indeed this was specific to autoconf 2.62 vs 2.64.  Running autoconfig
2.67 on said tester now, everything works smoothly.

Gerald