kbuild: version.h should depend on .kernelrelease

Rebuilding a previously built tree while using make's -j options from time to
time results in the version.h check running at the same time as the updating
of .kernelrelease, resulting in UTS_RELEASE remaining an empty string (and as
a side effect causing the entire kernel to be rebuilt).

Signed-Off-By: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -852,7 +852,7 @@ define filechk_version.h
 	)
 endef
 
-include/linux/version.h: $(srctree)/Makefile .config FORCE
+include/linux/version.h: $(srctree)/Makefile .config .kernelrelease FORCE
 	$(call filechk,version.h)
 
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