cbfstool: Make sure fileno is available on Cygwin

This patch fixes compilation of cbfstool on Cygwin.

As reported in http://review.coreboot.org/#/c/10027
cbfstool on Cygwin likes to be compiled with -D_GNU_SOURCE.
That patch was abandoned because it would unwantedly turn on
more GNU extensions. Instead of doing that, only enable the
define on Cygwin, switch to -std=gnu99 instead of -std=c99 to
make fileno and strdup actually available.
A MINGW32 check that was forgotten in Makefile was copied over
from Makefile.inc to keep the two files in sync.

This patch has no impact on non-Windows builds.

Change-Id: I068b181d67daf9c7280110e64aefb634aa20c69b
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/11667
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)

0 files changed, 0 insertions, 0 deletions