illumos gate

mdb does not at this time have a modulus operator, but it should. This is likely a hold over from adb. While there is a '%' operator, it is for integer division as the normal division operator '/' was taken due to dereferencing. As such, I've decided to co-opt '%%' to allow someone to have a modulus operator. This is currently invalid syntax.

To test this I put together a new mdb build and tested the following:

• We correctly calculated positive and negative modulus values in a way consistent with a C program or node.js.
• We correctly handled the modulus by zero case and errored
• We did not hit the division error that the division case special cases around LONG_MIN and -1.
• That we get a syntax error if missing either argument to the modulus operator or both
• Ran the mdb_v8 test suite as an additional sanity test

I also verified that on an older mdb, using the %% would always generate a syntax error, so it should not be possible to confuse it for something else.