MODSIGN: Add modules_sign make target

If CONFIG_MODULE_SIG is set, and 'make modules_sign' is called then this
patch will cause the modules to get a signature appended.  The make target
is intended to be run after 'make modules_install', and will modify the
modules in-place in the installed location.  It can be used to produce
signed modules after they have been processed by distribution build
scripts.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor typo fix)
diff --git a/Makefile b/Makefile
index 6cab75b..f00e0e3 100644
--- a/Makefile
+++ b/Makefile
@@ -981,6 +981,12 @@
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modinst
 	$(call cmd,depmod)
 
+ifeq ($(CONFIG_MODULE_SIG), y)
+PHONY += modules_sign
+modules_sign:
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modsign
+endif
+
 else # CONFIG_MODULES
 
 # Modules not configured