Index: configure.ac
===================================================================
--- configure.ac	(revision a5121bff2d239413034fc4cc466f9e5b15eebd1b)
+++ configure.ac	(revision 455a7d5b684d35263cb198930cc33e3f035b52ff)
@@ -7,7 +7,10 @@
 #AC_CONFIG_SRCDIR([src/main.cc])
 AC_CONFIG_HEADERS([config.h:src/config.h.in])
-AM_SILENT_RULES([no])
+AM_SILENT_RULES([yes])
 
 m4_include([automake/cfa.m4])
+
+# don't use the default CFLAGS as they unconditonnaly add -O2
+: ${CFLAGS=""}
 
 AM_INIT_AUTOMAKE([subdir-objects])