Missing pkg-config results in configure error: possibly undefined macro

This small article is for you who wonder why a configure script under Linux failed with an error like:

configure.ac:204: error: possibly undefined macro: AC_MSG_ERROR
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
configure.ac:216: error: possibly undefined macro: AC_CHECK_LIB
configure.ac:328: error: possibly undefined macro: AC_CHECK_HEADER
autoreconf: /usr/bin/autoconf failed with exit status: 1
 FAILED 

So autoreconf failed with missing macros, but you just saw you had the latest version and no clue what is wrong with the code you tried to compile!
In most cases the problem is trivial – you are missing the

pkg-config

It is a helper tool used when compiling. It helps to have the correct compiler options and not to hard-coded them in your files. So search for this tool in your Linux distro and install it.

Under CentOS 7

yum install pkgconfig

Under Ubuntu/Debian

apt-get install pkg-config

Under Gentoo

emerge -v dev-util/pkgconfig