* The '-g' flag are being passed in by CXXFLAGS and CFLAGS so ensure
that debugging builds are actually off by adding '-g0' to DEBUG_FLAGS.
* Add DEBUG_FLAGS to Python compiler options.
* Extract the flags from CXX and put into CXXFLAGS which is
passed into setup.py extra_compile_args.
* Remove now redundant os.environ test in setup.py
The flags supplied by libraries cannot be relied upon to be sane so
they all must be run through a parser to make sure search paths are
specified in the correct order.
Calum Lind