As Python 3 is the default Python version, change Boost to build against Python
3 instead of Python 2 if enabled. It's not simple to support both, so this
means that support for building boost-python against Python 2 has been removed.
This involves backporting a number of patches upstream to fix Python 3 support,
and telling Boost precisely where to find the Python headers and libraries so
that it doesn't try to invoke the host Python to determine these values.
[ YOCTO #11104 ]
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
