libpayload: Fix type issues

There were a number of type issues in libpayload that sneaked in
with 903f8e0.

- size_t and ssize_t were conflicting with gcc builtins
- some stdint types were used in libpayload but not defined
  in our stdint.h

With this patch it's possible to compile libpayload with the
reference toolchain again.

Change-Id: Idd5ccfdd9f3536b36bceca2d101e7405883b10bc
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2903
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
3 files changed