sched/getpid: replace syscall getpid/tid/ppid() to kernel version

NuttX kernel should not use the syscall functions, especially after
enabling CONFIG_SCHED_INSTRUMENTATION_SYSCALL, all system functions
will be traced to backend, which will impact system performance.

Signed-off-by: chao an <anchao@xiaomi.com>

include/execinfo.h

@@ -38,8 +38,9 @@
  * ARRAY and return the exact number of values stored.
  */
 
-# define backtrace(buffer, size) sched_backtrace(gettid(), buffer, size, 0)
-# define dump_stack()            sched_dumpstack(gettid())
+# define backtrace(buffer, size) sched_backtrace(_SCHED_GETTID(), \
+                                                 buffer, size, 0)
+# define dump_stack()            sched_dumpstack(_SCHED_GETTID())
 
 #else
 # define backtrace(buffer, size) 0