Index: configure.ac
===================================================================
--- configure.ac	(revision 158b026fb8f759ed1b6cebe96e8a07ccb25235cb)
+++ configure.ac	(revision 5c9b20cdbd8f11c2e3b1817c4e65a16c5f1e9a65)
@@ -14,4 +14,5 @@
 # don't use the default CFLAGS as they unconditonnaly add -O2
 : ${CFLAGS=""}
+: ${CXXFLAGS=""}
 
 AM_INIT_AUTOMAKE([subdir-objects])