fixed usage of unix-only attribute (fixed #3939)

tools/rosclean/src/rosclean/__init__.py

@@ -75,7 +75,7 @@ Commands:
 \trosclean check\tCheck usage of log files
 \trosclean purge\tRemove log files
 """)
-    sys.exit(os.EX_USAGE)
+    sys.exit(getattr(os, 'EX_USAGE', 1))
     
 def _get_check_dirs():
     home_dir = rospkg.get_ros_home()

tools/rosunit/scripts/check_test_ran.py

@@ -53,7 +53,7 @@ or
 \t%s --rostest pkg-name test-file.xml
 """%(NAME, NAME), file=sys.stderr)
     print(sys.argv)
-    sys.exit(os.EX_USAGE)
+    sys.exit(getattr(os, 'EX_USAGE', 1))
 
 def check_main():
     if len(sys.argv) < 2: