bitbake: Add a --revisions-changed commandline option to indicate when floating srcrevs have changed

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/bin/bitbake

@@ -108,6 +108,9 @@ Default BBFILES are the .bb files in the current directory.""" )
     parser.add_option( "-P", "--profile", help = "profile the command and print a report",
                action = "store_true", dest = "profile", default = False )
 
+    parser.add_option( "", "--revisions-changed", help = "Set the exit code depending on whether upstream floating revisions have changed or not",
+               action = "store_true", dest = "revisions_changed", default = False )
+
     options, args = parser.parse_args(sys.argv)
 
     configuration = BBConfiguration(options)