Drastically improve patching time.

[giulianobelinassi]

This PR refactors code in tools side so that livepatching is faster on a large number of processes.

Such changes include:

• Replace sprintf with strcpy to concatenate strings.
• Limit the number of symbols to check if a library is livepatchable.
• Reduce the amount of target processes reads.
• Add an optional cache to speedup symbol discovery.
• Replace ptrace with process_vm_writev/readv when possible.
• Reduce the number of attach/detach.
• Avoid wildcard matching if input is not a wildcard.
• Discover libpulp symbols in a separate thread.

• Add support to thread sanitizer.

  That changes reduces the trigger time on stress test (4000 processes) from 26.8s to 4.3s on an Intel Xeon E5 2670-v3.