[PATCH v2] CFLAGS: add -Wunused-but-set-parameter

[Alexey Dobriyan <adobriyan@gmail.com>]

-Wunused-but-set-parameter is finding stuff with current allmodconfig:

drivers/misc/mic/scif/scif_dma.c:118:27: warning: parameter 'ep' set but not used [-Wunused-but-set-parameter]
drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c:2156:8: warning: parameter 'function' set but not used [-Wunused-but-set-parameter]
drivers/net/ethernet/ti/tlan.c:1647:59: warning: parameter 'host_int' set but not used [-Wunused-but-set-parameter]
drivers/usb/gadget/udc/pxa27x_udc.c:1828:74: warning: parameter 'driver' set but not used [-Wunused-but-set-parameter]

and judging by changelogs, people were using it before,
but were too scared to change top level Makefile.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

	Can't compile gcc that old :-(

 Makefile |    3 +++
 1 file changed, 3 insertions(+)

--- a/Makefile
+++ b/Makefile
@@ -796,6 +796,9 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=date-time)
 # enforce correct pointer usage
 KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 
+# dead code
+KBUILD_CFLAGS += $(call cc-option,-Wunused-but-set-parameter,)
+
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)