libpayload: Include libpayload-config.h in lib target

- Added `$(obj)/libpayload-config.h` as a dependency for the `lib`
  target.
- This ensures the config header is up-to-date before building the
  library.

TEST=Able to build google/rex.

Change-Id: If26336f6261aadf611fa5338c4300873156cc3da
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82687
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>

0 files changed, 0 insertions, 0 deletions