- Enhanced SOAAP pass to add instrumentation for measuring
  sandboxing overhead.
  (soaap_perf library support to follow)
Code cleanup -- removed different ways used to apply instrumentation
and kept the most simple ones.
- Minor changes to SoaapPass.cpp.
- Updated soaap_perf.h to include the new function prototypes needed.
- Added bodies for the new functions that are used for perf
measurements.
Automatically make any persistent sandboxes to quit before the
program exits.
- Added support for __soaap_overhead(ARGUMENT) attribute. Developers
  may annotate a performance threshold that they are willing to
  accept for a specific sandbox and they will get a runtime warning
  if this is exceeded/violated.
Added a soaap_perf lib call that is used to compare the actual
sandboxing overhead to a threshold defined by the developer as
source code annotation.
Added Unix Domain Sockets as an IPC mechanism for performance
emulation.
Fixed a bug in SoaapPass perf emulation, in order to correctly
instrument functions with multiple BasicBlocks (and exit points).
Merged perf_analysis into master