A bunch of spot optmizations after cpu/memory profiling:
1. Optimize hot-path coverage comparison in fuzzer.
2. Don't allocate and copy serialized program, serialize directly into shmem.
3. Reduce allocations during parsing of output shmem (encoding/binary sucks).
4. Don't allocate and copy coverage arrays, refer directly to the shmem region
(we are not going to mutate them).
5. Don't validate programs outside of tests, validation allocates tons of memory.
6. Replace the choose primitive with simpler switches.
Choose allocates fullload of memory (for int, func, and everything the func refers).
7. Other minor optimizations.
Add sys/test.txt file with description of syscalls for tests.
These descriptions can be used to ensure that we can parse everything we clain we can parse.
Use these descriptions to write several tests for exec serialization
(one test shows that alignment handling is currently incorrect).
These test descriptions can also be used to write e.g. mutation tests.
Update #78
