environment variable that is defined when cross-compiling.

(directory for pid files etc, /run or /var/run).

https://lists.gnu.org/archive/html/bug-autoconf/2013-09/msg00002.html

Issue 27744: test_aes_cbc is blocking x86-64 Ubuntu 15.10 Skylake CPU 3.x for a while. Require Kernel 4.3+ for now

By Ivan Levkivskyi.

We should probably use pythontest.net for this.

Patch by py.user.

This commit contains the following commits from ghaering/pysqlite:

* https://github.com/ghaering/pysqlite/commit/f254c534948c41c0ceb8cbabf0d4a2f547754739
* https://github.com/ghaering/pysqlite/commit/796b3afe38cfdac5d7d5ec260826b0a596554631
* https://github.com/ghaering/pysqlite/commit/cae87ee68613697a5f4947b4a0941f59a28da1b6
* https://github.com/ghaering/pysqlite/commit/3567b31bb5e5b226ba006213a9c69dde3f155faf

With the following additions:

* Fixed a refcount error
* Fixed a compiler warning
* Made the string comparison a little more robust
* Added a whatsnew entry