We keep around WAF for node-waf only.
We need great diligence by people over the next couple weeks to work out all
the kinks in the GYP build system. We realize that it is currently several
times slower than the WAF build. Please lend a hand.
Older bash versions in `sh -c` mode don't parse `export FOO=42` constructs,
they bail out with a "FOO is not an identifier" error message.
This was fixed somewhere between bash 4.1.0 and 4.1.5 but let's support the
older versions anyway.