layout: Check return values for strdup in register_include_arg

strdup return values should be checked for NULL to catch the
potential error case of out of memory.

This patch re-writes ternary conditionals so that strdup return
values could be checked for all branches fof execution.

Follow up on
commit 45d50a101e8073191e6d88143990ed91d3bfe815

Ticket: https://ticket.coreboot.org/issues/372

Original-Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/70006
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Original-Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Original-Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
(cherry picked from commit 59ce5615b768fe9d4d2506cb13c6781cd83a12e6)

Change-Id: I6c22196be6847a8c9704f1de936604a51b4b8a28
Signed-off-by: Evan Benn <evanbenn@google.com>
---
M layout.c
1 file changed, 46 insertions(+), 3 deletions(-)