applied Bogdan's patch (closes SER-119), but there can be better solution (use flags independent on modules) - we will see

lib/Makefile.ser

@@ -2,7 +2,7 @@ include ../Makefile.defs
 
 # variables to change
 
-CFLAGS   += -g -Wall
+CFLAGS   :=${MOD_CFLAGS} -Wall
 DEFS     += -DSER
 ser      = $(CURDIR)/..