Make tracing tests work exactly as in CPython and compare the tracing results...

Make tracing tests work exactly as in CPython and compare the tracing results for both Python and Cython functions.
Fix "frame.f_trace" test in tracing code accordingly.
See #1769 and #1774 for background.

Cython/Utility/Profile.c

@@ -198,8 +198,7 @@
               PyThreadState *tstate;                                                       \
               PyGILState_STATE state = PyGILState_Ensure();                                \
               tstate = __Pyx_PyThreadState_Current;                                        \
-              if (unlikely(tstate->use_tracing && tstate->c_tracefunc                      \
-                  && __pyx_frame->f_trace != Py_None)) {                                   \
+              if (unlikely(tstate->use_tracing && tstate->c_tracefunc && $frame_cname->f_trace)) { \
                   ret = __Pyx_call_line_trace_func(tstate, $frame_cname, lineno);          \
               }                                                                            \
               PyGILState_Release(state);                                                   \
@@ -207,8 +206,7 @@
           }                                                                                \
       } else {                                                                             \
           PyThreadState* tstate = __Pyx_PyThreadState_Current;                             \
-          if (unlikely(tstate->use_tracing && tstate->c_tracefunc                          \
-                && __pyx_frame->f_trace != Py_None)) {                                     \
+          if (unlikely(tstate->use_tracing && tstate->c_tracefunc && $frame_cname->f_trace)) { \
               int ret = __Pyx_call_line_trace_func(tstate, $frame_cname, lineno);          \
               if (unlikely(ret)) goto_error;                                               \
           }                                                                                \
@@ -218,8 +216,7 @@
   #define __Pyx_TraceLine(lineno, nogil, goto_error)                                       \
   if (likely(!__Pyx_use_tracing)); else {                                                  \
       PyThreadState* tstate = __Pyx_PyThreadState_Current;                                 \
-      if (unlikely(tstate->use_tracing && tstate->c_tracefunc                              \
-                && __pyx_frame->f_trace != Py_None)) {                                     \
+      if (unlikely(tstate->use_tracing && tstate->c_tracefunc && $frame_cname->f_trace)) { \
           int ret = __Pyx_call_line_trace_func(tstate, $frame_cname, lineno);              \
           if (unlikely(ret)) goto_error;                                                   \
       }                                                                                    \