python: Make exception handling Python 3 safe

Change-Id: I9c2cdfad20deb1ddfa224320cf93f2105d126652
Reviewed-on: https://gem5-review.googlesource.com/c/15980
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>

src/python/m5/util/__init__.py

@@ -128,7 +128,7 @@ def compareVersions(v1, v2):
         elif isinstance(v, str):
             return map(lambda x: int(re.match('\d+', x).group()), v.split('.'))
         else:
-            raise TypeError
+            raise TypeError()
 
     v1 = make_version_list(v1)
     v2 = make_version_list(v2)
@@ -194,7 +194,7 @@ def readCommand(cmd, **kwargs):
     kwargs.setdefault('close_fds', True)
     try:
         subp = Popen(cmd, **kwargs)
-    except Exception, e:
+    except Exception as e:
         if no_exception:
             return exception
         raise
@@ -206,7 +206,7 @@ def makeDir(path):
     ensure that it is a directory"""
     if os.path.exists(path):
         if not os.path.isdir(path):
-            raise AttributeError, "%s exists but is not directory" % path
+            raise AttributeError("%s exists but is not directory" % path)
     else:
         os.mkdir(path)