LNT: Fix Perf profiling support

In Python3 the C interface has changed. [1]

During the upgrade the Creation of the perf
interface was upgraded to Python3 but the initialization
itself was not. As a consequence the module was not actually
registered and trying to use perf results in an error.

This would not be noticed as the import in the Python module
has the import in a try: .. except: pass block presumably
because perf support is optional.

[1] http://python3porting.com/cextensions.html

Reviewed By: thopre

Differential Revision: https://reviews.llvm.org/D93117

Author: TamarChristinaArm

lnt/testing/profile/cPerf.cpp

@@ -824,13 +824,15 @@ static PyModuleDef cPerfModuleDef = {PyModuleDef_HEAD_INIT,
                                      nullptr};
 #endif
 
-PyMODINIT_FUNC initcPerf(void) {
 #if PY_MAJOR_VERSION >= 3
+PyMODINIT_FUNC PyInit_cPerf(void) {
   return PyModule_Create(&cPerfModuleDef);
+}
 #else
+PyMODINIT_FUNC initcPerf(void) {
   (void)Py_InitModule("cPerf", cPerfMethods);
-#endif
 }
+#endif
 
 #else // STANDALONE
 

lnt/testing/profile/perf.py

@@ -7,7 +7,7 @@
 import traceback
 
 try:
-    import cPerf
+    from . import cPerf
 except Exception:
     pass