Start/Stop hook in apps

[svalat]

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Add hook support to start and stop instrumentation to track only a sub-part of the application.

[svalat]

The patch should be quite easy.

It requires to :

• capture call to two functions to start/stop instrumentation which might be named numaprof_instr_start/numaprof_instr_stop. Can look on malloc/free/realloc instrumentation.
• Add an option to start numaprof in stop mode when running with this (or automatically enable if found usage of the two previous symbols)
• Do not instrument memory accesses in ThreadTracker if in stop mode.

To be seen if we keep analysis of first touch of not (if we place the if/return at beginning of function of if/set skip.

Work is mainly here :

• https://github.com/memtt/numaprof/blob/master/src/integration/pintool/numaprof.cpp#L989
• https://github.com/memtt/numaprof/blob/master/src/lib/core/ThreadTracker.cpp#L239
• https://github.com/memtt/numaprof/blob/master/src/lib/core/ProcessTracker.hpp