In MachoPython, don't simulate argc/argv unless we have argc=1 and argv[1]

starts with "-psn_". This means the drag-and-drop continues to work as
expected, but we can now also do
/Applications/Python.app/Contents/MacOS/python script.py
from the command line, which is a lot easier with debugging. Pressing <option>
at this point also has the expected effect of opening the options dialog!

Mac/Python/macmain.c

@@ -316,8 +316,14 @@ init_common(int *argcp, char ***argvp, int embedded)
 		*argcp = 1;
 		*argvp = emb_argv;
 	} else {
-		/* Create argc/argv. Do it before we go into the options event loop. */
-		*argcp = PyMac_GetArgv(argvp, PyMac_options.noargs);
+		/* Create argc/argv. Do it before we go into the options event loop.
+		** In MachoPython we skip this step if we already have plausible
+		** command line arguments.
+		*/
+#if TARGET_API_MAC_OSX
+		if (*argcp == 2 && strncmp((*argvp)[1], "-psn_", 5) == 0)
+#endif
+			*argcp = PyMac_GetArgv(argvp, PyMac_options.noargs);
 #if !TARGET_API_MAC_OSX
 #ifndef NO_ARGV0_CHDIR
 		if (*argcp >= 1 && (*argvp)[0] && (*argvp)[0][0]) {