1. undefined reference to `free' (-Wl,--no-undefined doesn't work
   properly on OpenBSD + ld.lld)

2. Cherry pick trunk@13760, 13752 to remove boost::system
   per https://marc.info/?l=openbsd-ports&m=177038373917003&w=2

Index: configure.ac
--- configure.ac.orig
+++ configure.ac
@@ -15,7 +15,6 @@ AC_MSG_RESULT([${enable_flags_setting}])
 m4_include([m4/acinclude.m4])
 m4_include([m4/ax_cxx_compile_stdcxx.m4])
 m4_include([m4/ax_boost_base.m4])
-m4_include([m4/ax_boost_system.m4])
 
 CODEBLOCKS_CHECK_DEBUG
 
@@ -44,8 +43,6 @@ AC_PROG_AWK
 
 AX_CXX_COMPILE_STDCXX(11, noext)
 
-CODEBLOCKS_CHECK_LINK_FLAG([-Wl,--no-undefined],[LDFLAGS="-Wl,--no-undefined $LDFLAGS"])
-
 CODEBLOCKS_SETUP_FOR_TARGET
 
 dnl Checks for header files.
@@ -256,7 +253,6 @@ case $WX_BASENAME in
 		if test "x$BUILD_NASSISHNEIDERMAN_TRUE" = "x" ; then
 			dnl Check whether boost is installed
 			AX_BOOST_BASE
-			AX_BOOST_SYSTEM
 		fi
 
 		CB_GLIB2_CFLAGS="$GLIB2_CFLAGS"
