[LyX/master] Fix linking with std::regex and included boost

[Georg Baum]

commit 20a00903b1987b88239972b0cd9dedf45526548c
Author: Georg Baum <b...@lyx.org>
Date:   Sat Jun 11 10:09:48 2016 +0200

    Fix linking with std::regex and included boost

diff --git a/config/lyxinclude.m4 b/config/lyxinclude.m4
index c1b6524..d3405ed 100644
--- a/config/lyxinclude.m4
+++ b/config/lyxinclude.m4
@@ -393,7 +393,11 @@ AC_DEFUN([LYX_USE_INCLUDED_BOOST],[
        AC_MSG_RESULT([$lyx_cv_with_included_boost])
        if test x$lyx_cv_with_included_boost = xyes ; then
            BOOST_INCLUDES='-I$(top_srcdir)/3rdparty/boost'
-           BOOST_LIBS='$(top_builddir)/3rdparty/boost/liblyxboost.a'
+           if test $lyx_std_regex = yes ; then
+             BOOST_LIBS=""
+           else
+             BOOST_LIBS='$(top_builddir)/3rdparty/boost/liblyxboost.a'
+           fi
        else
            BOOST_INCLUDES=
            if test $lyx_std_regex = yes ; then