This reverts commit 20d0e3b3.

Fix building on macOS Sierra (10.12)

The -stdlib=libc++ flag is no longer supported on Sierra (it is now the
default option). I added a version check that adds the option for macOS
versions below Sierra (10.12) and removed the option otherwise.

Use WriteOncePersistentDict instead of PersistentDict.

See merge request inducer/pyopencl!23

Fix vector-typed memory maps (#203 on github)

See merge request !22

This reverts commit dcb5d701.

Prepare for Py3.7's marking 'async' a reserved keyword

See merge request !21

Fixed a typo in function documentation.

Fixes for testing single-precision devices.

Some OpenCL implementations break if event list is empty.

Add -Wl,--no-as-needed to Linux builds by default to support Altera FPGAs more easily (#132 on Github)

pyopencl.scan: Add support for on-disk caching of generated code

See merge request !18