remove default debug and warning flags
--- configure.ac.orig	2018-05-24 08:24:31.000000000 -0700
+++ configure.ac	2019-01-26 23:50:37.000000000 -0700
@@ -80,7 +80,7 @@
 # set CFLAGS and CXXFLAGS
 #user_CFLAGS="${CXXFLAGS}"
 user_CFLAGS=${CFLAGS}
-generic_CFLAGS="-Wall -Wno-strict-aliasing -g -gdwarf-2 -Wuninitialized"
+generic_CFLAGS=""
 ext_CFLAGS=""
 debug_CFLAGS=""
 user_LDFLAGS="$LDFLAGS"