Both SDK 0.10.0-beta2 and the ARM gcc 2018q2 run into a build issue with
newlib and conflict definitions of mode_t type.
First we need to add some ifdef protection if mode_t is already defined
and set _MODE_T_DECLARED if we are the first to define it.
Secondarily, we rename include/posix/sys/types.h to
include/posix/posix_types.h so that we aren't getting a name collusion
with the system sys/types.h and that we can easily and clearily include
it (which we need to do to pull in the info from newlib).
Fixes: #12224
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
e96d02984c