1. Express desired path.join behavior in tests.
2. Update fs.realpath to reflect new path.join behavior
3. Update url.resolve() to use new path.join behavior.

writeFileSync could exhibit pathological behavior when a buffer could
not be written to the file in a single write() call.

Also, writeFile was not quite as optimized as it could be.

Added support for cross compilation and also fixed DEST_CPU to represent the canonical symbols dictated by v8

Plus random cleanups. This code needs help.

Now that we insert \r into the stream and aren't switching back and forth
between termios modes, not need to worry about when to display the prompt.

Switch \n with \r\n for all strings printed out.
Necessary for writev patch.

Use process.stdout.write()

With regression test.

Already fixed in 7e24a05c

Too much instability right now. Hopefully we can revisit autoconf soon.