Re-export header files only if either they or their controlling Kbuild
file has actually changed. Also allow for similar dependencies with
'headers_check', once we properly create the dependencies for those.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The following combinations of pp-tokens are used

	#include
	 #include
	# include

so, script'd better check for all of them.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Based on the 'headers_install' target, this performs a basic sanity check
on the exported headers -- so far only checking that they do not include
any other headers which aren't selected for import, but easily extendable.
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>