Enhancements on wasm function execution time statistic (#2985)

Enhance the statistic of wasm function execution time, or the performance
profiling feature:
- Add os_time_thread_cputime_us() to get the cputime of a thread,
  and use it to calculate the execution time of a wasm function
- Support the statistic of the children execution time of a function,
  and dump it in wasm_runtime_dump_perf_profiling
- Expose two APIs:
  wasm_runtime_sum_wasm_exec_time
  wasm_runtime_get_wasm_func_exec_time

And rename os_time_get_boot_microsecond to os_time_get_boot_us.

core/iwasm/fast-jit/fe/jit_emit_control.c

@@ -396,9 +396,8 @@ handle_func_return(JitCompContext *cc, JitBlock *block)
 #endif
 
 #if WASM_ENABLE_PERF_PROFILING != 0
-    /* time_end = os_time_get_boot_microsecond() */
-    if (!jit_emit_callnative(cc, os_time_get_boot_microsecond, time_end, NULL,
-                             0)) {
+    /* time_end = os_time_get_boot_us() */
+    if (!jit_emit_callnative(cc, os_time_get_boot_us, time_end, NULL, 0)) {
         return false;
     }
     /* time_start = cur_frame->time_started */