Index: configure.ac
===================================================================
--- configure.ac	(revision 158b026fb8f759ed1b6cebe96e8a07ccb25235cb)
+++ configure.ac	(revision e068c8a8da15b590c9ee6dc1bf9fefcffcc2b1dc)
@@ -14,4 +14,5 @@
 # don't use the default CFLAGS as they unconditonnaly add -O2
 : ${CFLAGS=""}
+: ${CXXFLAGS=""}
 
 AM_INIT_AUTOMAKE([subdir-objects])