Thread-safe error location in maintainer mode

There was some discussion on #svn-dev recently about making the error
location tracing (see libsvn_subr/error.c and svn_error__locate)
thread-safe, by using platform- and compiler-specific flags for making
the location variables thread-safe.

It turns out that, since we now require APR 1.3+ which provides
unmanaged pools, we can now safely do this by using APR's threadkey API.
See:

    https://paste.apache.org/fG82

With this patch, all tests pass for on my Mac in parallel mode and the
error stacks look sane. But, before committing the change, I'd like
someone else to review the patch because it's just a wee bit tricky in
places what with all the #ifdefs.

-- Brane
Received on 2015-03-04 09:28:24 CET