set AFL_PATH to point to the correct afl_tracer

[pwnslinger]

After reviewing the PR#2 in afl-other-archs, we decided to embed arch detection capability in fuzzer module, instead of using a bash script to set the correct afl_path env var.

Also I made simple change in shellphuzz to support memory limitation that I have countered during some of my test cases.

Finally, I added a new whole test to test_fuzzer script in order to completely check all binaries with various claimed supported archs which would be useful in near future (I am working on angr-platforms repo to enhance lifter/archinfo).

I would be so thankful if you double check the enhancement, since it's my first contribution and I am stressed out...

Special thanks to @Jacopo and @ltfish, those guys are really awesome <3