Tiny modification to m4/boost.m4.

m4/boost.m4

 # boost.m4: Locate Boost headers and libraries for autoconf-based projects.
 # Copyright (C) 2007, 2008, 2009  Benoit Sigoure <tsuna@lrde.epita.fr>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 #
 # Additional permission under section 7 of the GNU General Public
 # License, version 3 ("GPLv3"):
@@ skipping 49 matching lines @@
 AC_LANG_CONFTEST([AC_LANG_SOURCE([[$2]])])
 AS_IF([dnl eval is necessary to expand ac_cpp.
 dnl Ultrix and Pyramid sh refuse to redirect output of eval, so use subshell.
 dnl Beware of Windows end-of-lines, for instance if we are running
 dnl some Windows programs under Wine.  In that case, boost/version.hpp
 dnl is certainly using "\r\n", but the regular Unix shell will only
 dnl strip `\n' with backquotes, not the `\r'.  This results in
 dnl boost_cv_lib_version='1_37\r' for instance, which breaks
 dnl everything else.
 dnl Cannot use 'dnl' after [$4] because a trailing dnl may break AC_CACHE_CHECK
-(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
+(eval "$ac_cpp $CXXFLAGS conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
   tr -d '\r' |
   $SED -n -e "$1" >conftest.i 2>&1],
   [$3],
   [$4])
 rm -rf conftest*
 ])# AC_EGREP_CPP
 
 
 
 # BOOST_REQUIRE([VERSION], [ACTION-IF-NOT-FOUND])
@@ skipping 948 matching lines @@
 dnl Delete also the IPA/IPO (Inter Procedural Analysis/Optimization)
 dnl information created by the PGI compiler (conftest_ipa8_conftest.oo),
 dnl as it would interfere with the next link command.
 rm -f core conftest.err conftest_ipa8_conftest.oo \
       conftest$ac_exeext m4_ifval([$1], [conftest.$ac_ext])[]dnl
 ])# _BOOST_AC_LINK_IFELSE
 
 # Local Variables:
 # mode: autoconf
 # End: