SNMP++, AGENT++, and AgentX++ require autoconf version 2.64 or higher. Version 2.69 is recommended. If your system does not provide version 2.69 out of the box, you can install it used the following steps.

Install autoconf 2.69
wget http://ftp.gnu.org/gnu/autoconf/autoconf-2.69.tar.gz  
tar xvfvz autoconf-2.69.tar.gz  
cd autoconf-2.69  
./configure  
make  
sudo make install  


Autoconf for Mac OS X

Install Autoconf Tools for SNMP+/AGENT+ on Mac OS X
curl -O -L http://ftpmirror.gnu.org/autoconf/autoconf-2.69.tar.gz
tar xvf autoconf-2.69.tar.gz 
cd autoconf-2.69
./configure 
make
sudo make install
autoconf --version
cd ..
curl -O -L http://ftpmirror.gnu.org/automake/automake-1.15.tar.gz
tar -xzf automake-1.15.tar.gz 
cd automake-1.15
./configure 
make
sudo make install
cd ..
curl -OL http://ftpmirror.gnu.org/libtool/libtool
cd libtool-2.4.6.tar.gz 
tar -xzf libtool-2.4.6.tar.gz 
cd libtool-2.4.6
./configure 
make
sudo make install
cd ..
tar -xzf pkg-config-0.29.2.tar 
cd pkg-config-0.29.2
./configure 
make
./configure --prefix=/usr/local CC=$CC --with-internal-glib
make
sudo make install