about threads support in 1.7.11 breaking 3rd party modules

[Ruslan Ermilov]

In version 1.7.11 we have implemented threads support, please see
http://nginx.org/r/aio for details.

For this, we reused the NGX_THREADS macro that was unused on UNIXes
since 1.0.4 (June 2011).

This caused some 3rd party modules fail to compile if threads were
enabled:

https://lists.freebsd.org/pipermail/svn-ports-all/2015-April/090158.html

The analysis have shown that breakages fall into two categories:

17 out of 20 broken modules failed to compile because they didn't
include <ngx_config.h> before including <ngx_core.h> in some cases.

The remaining 3 modules were failing because they still used the
NGX_THREADS macro with some long unused code.  The corresponding
code can be safely removed.

If you're the maintainer of the broken module, please fix it.