Basic implementation of 'make headers_check'

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: David Woodhouse <dwmw2@infradead.org>

scripts/hdrcheck.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+for FILE in `grep '^#include <' $2 | cut -f2 -d\< | cut -f1 -d\> | egrep ^linux\|^asm` ; do
+    if [ ! -r $1/$FILE ]; then
+	echo $2 requires $FILE, which does not exist
+	exit 1
+    fi
+done