Funtion fstat will return -1 if there's any error, 0 if successful.
Check that fstat return is equal to 0, print error message and exit if
not 0.
This fixes CIDs 1353018 and 1353020
BUG=b:72062481
TEST=Build no errors
Change-Id: I83284d9125c75a29471f213f88b9181d5edba2e6
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-on: https://review.coreboot.org/23827
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
7b89a28149