crypto: add preemptive threading support

Some primitives are designed to be used in a multi-threaded environment,
if supported, e.g., Argon2.

This patch adds support for preemptive threading and basic synchronization
primitives for platforms compliant with POSIX threads or Windows CRT.
Native functions are wrapped to provide a common (internal) API.

Threading support can be disabled at compile time. If enabled, threading
is disabled by default and needs to be explicitly enabled by the user.

Thread enablement requires an explicit limit on the number of threads that
OpenSSL may spawn (non-negative integer/infinity). The limit may be changed.

Signed-off-by: Čestmír Kalina <ckalina@redhat.com>

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12255)

0 files changed, 0 insertions, 0 deletions