Android uses MinGW for some host tools on Windows. That toolchain
doesn't support the #pragma tricks we use for thread-local destructors,
but does appear to support pthreads.

This also lets us remove the INIT_ONCE workaround, although that's
removable anyway since Android's MinGW is now new enough.

Change-Id: I8d1573923fdaac880a50d84acbebbf87461c50d2
Reviewed-on: https://boringssl-review.googlesource.com/11125
Reviewed-by: David Benjamin <davidben@google.com>
Reviewed-by: Kenny Root <kroot@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

Windows SRWLOCK requires you call different functions here. Split
them up in preparation for switching Windows from CRITICAL_SECTION.

BUG=37

Change-Id: I7b5c6a98eab9ae5bb0734b805cfa1ff334918f35
Reviewed-on: https://boringssl-review.googlesource.com/8080
Reviewed-by: Adam Langley <agl@google.com>

The |fprintf| dependency is quite heavyweight for small targets. Also,
using |fprintf| on a closed file dsecriptor is undefined behavior, and
there's no way that this code can know whether |stderr| has already
been closed. So, just don't do it.

Change-Id: I1277733afe0649ae1324d11cac84826a1056e308
Reviewed-on: https://boringssl-review.googlesource.com/6812
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>

It can fail on FreeBSD when library is not linked against either
threading library and results in init routine not being executed
at all, leading to errors in other parts of the code.

Change-Id: I1063f6940e381e6470593c063fbfecf3f47991cd
Signed-off-by: Piotr Sikora <piotrsikora@google.com>
Reviewed-on: https://boringssl-review.googlesource.com/6522
Reviewed-by: Adam Langley <agl@google.com>

Trusty doesn't have setjmp.h and nor does it have threads.

Change-Id: I005f7a009a13e6632513be9fab2bbe62294519a4
Reviewed-on: https://boringssl-review.googlesource.com/4660
Reviewed-by: Adam Langley <agl@google.com>

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>

Historically, OpenSSL has used callbacks for anything thread related,
but we don't actually have that many threading libraries to worry about:
just pthreads and Windows (I hope).

That suggests that it's quite reasonable to handle threading ourselves,
and eliminate the need for users to remember to install the thread
callbacks.

The first user of this would be ERR, which currently simulates
thread-local storage using a lock around a hash table keyed by the TID.
(Although I suspect that change will need some CMake work in order that
libpthread is automatically included with libcrypto when linking tests
etc, but not on Windows and without lots of ifs.)

Change-Id: I4dd088e3794506747f875c1f3e92b9bc6700fad2
Reviewed-on: https://boringssl-review.googlesource.com/4010
Reviewed-by: Adam Langley <agl@google.com>