support source and pyenv or venv python3 homes

Author: timfel

mx.graalpython/mx_graalpython_python_benchmarks.py

@@ -238,6 +238,10 @@ def interpreter(self):
             return sys.executable
         if exists(exe := join(home, "bin", "python3")):
             return exe
+        elif exists(exe := join(home, "python3")):
+            return exe
+        elif exists(exe := join(home, "python")):
+            return exe
         return join(home, "bin", "python")
 
     def run(self, cwd, args):