kbuild: Fix silent builds with make-4

make-4 changed the way/order it presents the command line options
into MAKEFLAGS

In make-3.8x, '-s' would always be first into a group of options
with the '-'/hyphen removed

$ make -p -s 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = sp

In make-4, '-s' seems to always be last into a group of options
with the '-'/hyphen removed

$ make -s -p 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = ps
Signed-off-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -311,9 +311,15 @@ endif
 # If the user is running make -s (silent mode), suppress echoing of
 # commands
 
+ifneq ($(filter 4.%,$(MAKE_VERSION)),)	# make-4
+ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
+  quiet=silent_
+endif
+else					# make-3.8x
 ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
   quiet=silent_
 endif
+endif
 
 export quiet Q KBUILD_VERBOSE