ext-testlib: Support str-convertible args in gem5_verify_config

gem5_verify_config dit not support string-convertible args due to log_call()
not trying to call str() on them. This patch maps str() on the command
paramters.

It is now possible to pass native integers or even string-like types like
pathlib.Path as arguments without manually converting them to string.

Change-Id: Ifa987f5f1a20f17c8710e1a36d99d424e4c9ce6c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/66893
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

ext/testlib/helper.py

@@ -149,7 +149,14 @@ def log_call(logger, command, time, *popenargs, **kwargs):
     if isinstance(command, str):
         cmdstr = command
     else:
-        cmdstr = ' '.join(command)
+        try:
+            command = list(map(str, command))
+            cmdstr = " ".join(command)
+        except TypeError as e:
+            logger.trace(
+                "Argument <command> must be an iterable of string-convertible types"
+            )
+            raise e
 
     logger_callback = logger.trace
     logger.trace('Logging call to command: %s' % cmdstr)