utils/add-custom-hashes: symlink linux-headers to linux

Most boards use BR2_KERNEL_HEADERS_AS_KERNEL with their custom kernels.
So when creating their custom hash files, the linux-headers.hash is the
same as linux.hash. In this case we symlink linux-headers to linux to
make maintenance easier. Update the add-custom-hashes tool to explicitly
handle this case.

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
[Peter: use cmp -s]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit d506e232e7388e70622a1c1b2a3069367d7b305b)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/add-custom-hashes

@@ -97,6 +97,14 @@ for file in $BR_NO_CHECK_HASH_FOR; do
     done
 done
 
+# Symlink linux-headers to linux if identical
+linux_hash="$BR2_GLOBAL_PATCH_DIR/linux/linux.hash"
+linux_headers_hash="$BR2_GLOBAL_PATCH_DIR/linux-headers/linux-headers.hash"
+if [ -e "$linux_hash" ] && [ -e "$linux_headers_hash" ] \
+    && cmp -s "$linux_hash" "$linux_headers_hash"; then
+    ln -sf ../linux/linux.hash "$linux_headers_hash"
+fi
+
 message Verifying hashes
 
 make clean