Autoconf version?



What is the version of autoconf that is needed for compiling maxima?

I've been using autoconf 2.5 and that works fine.  But on a Solaris box, 
the default version of grep doesn't understand -e, which breaks the 
build of the info files.

I'd like to add an autoconf check to find a version of grep that 
understands -e, but that needs AC_PROG_GREP, which doesn't seem to be 
available in 2.50.

Ray