Initial merge of filtering/lua/asinfo GSoC 2017 projects

[Eugene Syromiatnikov]

Hello.

As GSoC 2017 nearing its completion, I decided that it's time to try to
look at the merged version of the code.  You can have a look at the
results of my attempt at [1]. Some notes:
 * As expected, most conflicts are between Victor's and Nikolay's work.
   Edgar's part is applying without any conflicts.
 * Since umove* functions have been moved to ucopy.c along with some
   changes, I decided to do the same with upoke*.
 * Current handling of hook_entry/hook_exit inside filter_syscall is a
   kludge.  On the other hand, proper integration of Lua into the new
   filtering scheme is a bit of a stretch task.
 * I had to duplicate filter_syscall call in luajit.h, which again
   makes me think that func_next_sc should be refactored.
 * It successfully builds and passes tests (at least, on my x86_64
   machine), but the value of this fact depends largely on the quality
   and quantity of supplied tests.

[1] https://github.com/esyr-rh/strace/tree/esyr/gsoc2017-merge