Previous commits attempted to use `gmtime_s()` for IAR systems; however,
this attempt depends on the use of C11 extensions which lead to incompatibility
with other pieces of the library, such as the use of `memset()` which is
being deprecated in favor of `memset_s()` in C11.
Protecting the ECP hardware acceleratior with mutexes is inconsistent with the
philosophy of the library. Pre-existing hardware accelerator interfaces
leave concurrency support to the underlying platform.
Fixes#863
The primary use case behind providing an abstraction layer to enable
alternative Elliptic Curve Point arithmetic implementation, is making
use of cryptographic acceleration hardware if it is present.
To provide thread safety for the hardware accelerator we need a mutex
to guard it.
* gmtime_r is not standard so -std=c99 warns about it
* Anyway we need global mutexes in the threading layer, so better depend only
on that, rather that global mutexes + some _r functions
