Prior to this, BoringSSL was using OpenSSL's technique of having users
register a callback for locking operation. This change adds native mutex
support.
Since mutexes often need to be in objects that are exposed via public
headers, the non-static mutexes are defined in thread.h. However, on
Windows we don't want to #include windows.h for CRITICAL_SECTION and, on
Linux, pthread.h doesn't define pthread_rwlock_t unless the feature
flags are set correctly—something that we can't control in general
for public header files. Thus, on both platforms, the mutex is defined
as a uint8_t[] of equal or greater size and we depend on static asserts
to ensure that everything works out ok.
Change-Id: Iafec17ae7e3422325e587878a5384107ec6647ab
Reviewed-on: https://boringssl-review.googlesource.com/4321
Reviewed-by: Adam Langley <agl@google.com>
df1f5e796c