Upgrade to waf 1.8.4.

This version adds support for `clang` and `clang++` compilers on
Linux and OSX so that they can be used directly and not just when
the `gcc` and `g++` commands actually map to Clang.

Tested on Linux, Solaris, AIX, and Windows.

Signed-off-by: Andrew Paprocki <andrew@ishiboo.com>
Fix support for CXX and CC environment variables

Waf 1.8.4 uses the CXX and CC environment variables in ctx.environ
instead of directly from os.environ.  ctx.environ is initialized from
os.environ on start up, so modifying os.environ later will not affect
waf's view of environment variables.  Change bdewscript.py to update
ctx.environ instead of os.environ when updating the values of CC and
CXX.
Patch waf 1.8.4 to fix support for CXX & CC on sun

waf 1.8.0 - 1.8.4 has a bug that prevents CC and CXX environment
variables from being considered when loading sun studio compilers. Patch
this locally until this is officially fixed.