bpo-36184: Port python-gdb.py to FreeBSD (GH-18873)

python-gdb.py now checks for "take_gil" function name to check if a
frame tries to acquire the GIL, instead of checking for
"pthread_cond_timedwait" which is specific to Linux and can be a
different condition than the GIL.

Misc/NEWS.d/next/Tools-Demos/2020-03-09-13-28-13.bpo-36184.BMPJ0D.rst

@@ -0,0 +1,4 @@
+Port python-gdb.py to FreeBSD. python-gdb.py now checks for "take_gil"
+function name to check if a frame tries to acquire the GIL, instead of
+checking for "pthread_cond_timedwait" which is specific to Linux and can be
+a different condition than the GIL.

Tools/gdb/libpython.py

@@ -1600,7 +1600,7 @@ class Frame(object):
         # This assumes the _POSIX_THREADS version of Python/ceval_gil.h:
         name = self._gdbframe.name()
         if name:
-            return 'pthread_cond_timedwait' in name
+            return (name == 'take_gil')
 
     def is_gc_collect(self):
         '''Is this frame "collect" within the garbage-collector?'''