C locking callback (#3226)

* Remove Python OpenSSL locking callback and replace it with one in C

The Python OpenSSL locking callback is unsafe; if GC is triggered
during the callback's invocation, it can result in the callback being
invoked reentrantly, which can lead to deadlocks. This patch replaces
it with one in C that gets built at compile time via cffi along with
the rest of the OpenSSL binding.

* fixes for some issues

* unused

* revert these changes

* these two for good measure

* missing param

* sigh, syntax

* delete tests that assumed an ability to mess with locks

* style fixes

* licensing stuff

* utf8

* Unicode. Huh. What it isn't good for, absolutely nothing.

1 files changed, 41 insertions, 0 deletions

diff --git a/LICENSE.PSF b/LICENSE.PSF
new file mode 100644
index 00000000..4d3a4f57
--- /dev/null
+++ b/LICENSE.PSF
@@ -0,0 +1,41 @@
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