kbuild: Fix path to scripts/setlocalversion

Commit 0a564b26 broke LOCALVERSION for O=... builds. Ouch.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-by: Peter Anvin <hpa@zytor.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Makefile

@@ -886,7 +886,7 @@ $(vmlinux-dirs): prepare scripts
 # Store (new) KERNELRELASE string in include/config/kernel.release
 include/config/kernel.release: include/config/auto.conf FORCE
 	$(Q)rm -f $@
-	$(Q)echo "$(KERNELVERSION)$$($(CONFIG_SHELL) scripts/setlocalversion $(srctree))" > $@
+	$(Q)echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))" > $@
 
 
 # Things we need to do before we recursively start building the kernel