This describes their purpose better, as we now initialize ssl and some
other global stuff in there. Calling the init function is not something
which has been optional for a while now.
Increasingly there are a number of components that want to do some
cleanup at global shutdown time (at least if there are not going
to be memory leaks). This creates a very simple system of shutdown
hooks that will be invoked by git_threads_shutdown. Right now, the
maximum number of hooks is hardcoded, but since adding a hook is
not a public API, it should be fine and I thought it was better to
start off with really simple code.
This loads SRWLock APIs at runtime and in their absence (i.e. on
Windows before Vista) falls back on a regular CRITICAL_SECTION
that will not permit concurrent readers.
