This reverts commit 20d0e3b3.

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.

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

Added CL_USE_SHIPPED_EXT Switch in setup.py to use src/c_wrapper/clinfo_ext.h instead of CL/cl_ext.h.

Recommended here:
https://cplusplusmusings.wordpress.com/2012/07/05/clang-and-standard-libraries-on-mac-os-x/

This fixes an insecure temporary file creation bug on UNIX-like systems.