RB_HELP_STRING([--with-boost-chrono@<:@=special-lib@:>@], [use the Chrono library from boost - it is possible to specify a certain library for the linker e.g. --with-boost-chrono=boost_chrono-gcc-mt ]),
AC_DEFINE(HAVE_BOOST_CHRONO,,[define if the Boost::Chrono library is available])
BOOSTLIBDIR=`echo $BOOST_LDFLAGS | sed -e 's/@<:@^\/@:>@*//'`
LDFLAGS_SAVE=$LDFLAGS
if test "x$ax_boost_user_chrono_lib" = "x"; then
for libextension in `ls $BOOSTLIBDIR/libboost_chrono*.so* $BOOSTLIBDIR/libboost_chrono*.dylib* $BOOSTLIBDIR/libboost_chrono*.a* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^lib\(boost_chrono.*\)\.so.*$;\1;' -e 's;^lib\(boost_chrono.*\)\.dylib.*$;\1;' -e 's;^lib\(boost_chrono.*\)\.a.*$;\1;'` ; do
for libextension in `ls $BOOSTLIBDIR/boost_chrono*.dll* $BOOSTLIBDIR/boost_chrono*.a* 2>/dev/null | sed 's,.*/,,' | sed -e 's;^\(boost_chrono.*\)\.dll.*$;\1;' -e 's;^\(boost_chrono.*\)\.a.*$;\1;'` ; do