Revert "Revert "FROMLIST: kheaders: Follow symlinks to source files.""

This reverts commit 3ee567f.

Reason for revert: relanding change

When the kernel is built inside a sandbox container,
a forest of symlinks to the source files may be
created in the container. In this case, the generated
kheaders.tar.xz should follow these symlinks
to access the source files, instead of packing
the symlinks themselves.

After this change, kheaders_data.tar.xz increases from
132K to 6.7M for Bazel builds on android-mainline.

Bug: 283225390
Bug: 276339429
Link: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Yifan Hong <[email protected]>
Change-Id: I8fe7c02ce9a7dd355cc96df53be23dcb870e3c57

Author: Yifan Hong

kernel/gen_kheaders.sh

@@ -87,7 +87,7 @@ find $cpio_dir -type f -print0 |
 # pre-sorted, as --sort=name might not be available.
 find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \
     tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
-    --owner=0 --group=0 --numeric-owner --no-recursion \
+    --owner=0 --group=0 --numeric-owner --no-recursion --dereference \
     -I $XZ -cf $tarfile -C $cpio_dir/ -T - > /dev/null
 
 echo $headers_md5 > kernel/kheaders.md5