[boost] AC_PATH_BOOST to find Boost headers from an autoconf script

From: Douglas Gregor (gregod_at_[hidden])
Date: 2002-10-09 18:15:18

The attached m4 macro AC_PATH_BOOST helps locate an existings Boost 
installation from an autoconf configure script. The macro "prototype" is:

AC_PATH_BOOST(boost-version, action-if-found, action-if-not-found)

The macro looks for the Boost libraries at the path specified via the 
command-line parameter --with-boost=<path> or at the path in the BOOST_ROOT 
environment variable. If Boost is found, the version is checked against the 
given version. The macro exports BOOST_ROOT (the location where the Boost 
libraries were found) and BOOST_CXXFLAGS (flags needed to compile with 
Boost).

Sample usage (in configure.in/configure.ac):
  AC_PATH_BOOST(1.28.0, , AC_MSG_ERROR([Package requires the Boost C++ 
libraries!]))

        Doug