Automatically adjust ARFLAGS so "make -s" is really silent.

config.mk

@@ -127,7 +127,11 @@ OBJCOPY = $(CROSS_COMPILE)objcopy
 OBJDUMP = $(CROSS_COMPILE)objdump
 RANLIB	= $(CROSS_COMPILE)RANLIB
 
+ifneq (,$(findstring s,$(MAKEFLAGS)))
+ARFLAGS = cr
+else
 ARFLAGS = crv
+endif
 RELFLAGS= $(PLATFORM_RELFLAGS)
 DBGFLAGS= -g # -DDEBUG
 OPTFLAGS= -Os #-fomit-frame-pointer