for some early versions of re2.

Also get rid of an unnecessary #include "config.h".

Mention autoconf-archive and C++ build requirements and setting
ACLOCAL_PATH.

Closes #2

Please replace this with a better solution if known:

When re2 is installed in a non-standard location, pkg-config --libs re2
(as invoked by PKG_CHECK_MODULES) returns -L<path>, but not -R<path>,
so we fix it up to get the right rpath in the vmod so.

Closes !1

References merge request !1

This reverts commit 35e21c5f.

No longer needed since the fix for Varnish issue 2449.

See Varnish issue #2449

space for task-scoped match data from workspace.

no longer using pthread keys.

the year.