Treat './mach package' as a steps.Compile

Even when this command fails, Buildbot still goes on to run the next
step, because it is run as a simple ShellCommand.

Instead, we now check for it in the `make_step` function and use
`steps.Compile` to create the step as it is not only a closer semantic
match (we're "compiling" the package) but it also makes it so when it
fails Builbot doesn't ignore it or move on to the next step.

buildbot/master/files/config/factories.py

@@ -106,6 +106,8 @@ def make_step(self, command):
                 step_desc = [mach_arg]
                 if re.match('build(-.*)?', mach_arg):
                     step_class = steps.Compile
+                elif re.match('package', mach_arg):
+                    step_class = steps.Compile
                 elif re.match('test-.*', mach_arg):
                     step_class = steps.Test
 
@@ -251,6 +253,8 @@ def make_step(self, command):
                 step_desc = [mach_arg]
                 if re.match('build(-.*)?', mach_arg):
                     step_class = steps.Compile
+                elif re.match('package', mach_arg):
+                    step_class = steps.Compile
                 elif re.match('test-.*', mach_arg):
                     step_class = steps.Test