Support sampling duration, sampling TIDs (#142)

- Sampling duration config values
  - OMNITRACE_SAMPLING_DURATION
  - OMNITRACE_PROCESS_SAMPLING_DURATION
  - Disables sampling after this time (in seconds) has elapsed 
- Sampling thread-id config values
  - OMNITRACE_SAMPLING_TIDS
  - OMNITRACE_SAMPLING_CPUTIME_TIDS
  - OMNITRACE_SAMPLING_REALTIME_TIDS
  - Allows user to select certain threads for sampling
- Miscellaneous
  - Tweaked the finalization verbosity messages
  - moved sampling-on-child-threads into runtime.hpp and runtime.cpp
  - fixed submodule dyninst header install

source/lib/omnitrace/library/cpu_freq.cpp

@@ -160,8 +160,9 @@ write_perfetto_counter_track(index&& _idx, Args... _args)
 void
 post_process()
 {
-    OMNITRACE_PRINT("Post-processing %zu cpu frequency and memory usage entries...\n",
-                    cpu_data.size());
+    OMNITRACE_VERBOSE(1,
+                      "Post-processing %zu cpu frequency and memory usage entries...\n",
+                      cpu_data.size());
     auto _process_frequencies = [](size_t _idx, size_t _offset) {
         using freq_track = perfetto_counter_track<cpu_freq_component>;