Update: replace MD5 hashing of cache files with MurmurHash (fixes #5522)

[michaelficarra]

Fixes #5522. Removes the dependency on the crypto module, which is not available when node is built with the --without-ssl flag.

[eslintbot]

LGTM

[BYK]

Nice! LGTM.

[ilyavolodin]

LGTM. @nzakas could you take a look?

[nzakas]

Can someone test this with --cache, seeing what happens when you have an existing cache and then upgrade to this?

[jbergstroem]

FWIW, LGTM. On top of @nzakas comment a benchmark would perhaps also be interesting?

[ilyavolodin]

Just ran this on a local code. Works perfectly fine when cache was created with current ESLint implementation and the next run is done with this PR. It basically just lints all files first time around. It's really tough to measure performance difference, since my sample code is small enough where running it with cache is actually slower then normal run.

[jbergstroem]

Just did a very unscientific benchmark on invoking time make lint in the nodejs repo five times with and without the patch. Looks like the switch was insignificant from a performance point of view. Results below:

timing	crypto('md5')	imurmurhash
fastest run	16.91s	16.62s
slowest run	18.01s	17.85s

[nzakas]

@michaelficarra can you rebase?

[michaelficarra]

@nzakas done.