Use process-specific name for dm devices.

If you're doing e.g. an i386 build an an x86_64 build at the same time,
you wind up deadlocking the dmsetup processes in sys_semtimedop()
because they have the same name between the two codepaths. This is
probbaly a dmsetup bug, but even if it weren't, you'd still have two
composes trying to use the same dm devices, and that's bad.  Instead,
stick the pid in the names.

src/pylorax/__init__.py

@@ -689,7 +689,8 @@ class Lorax(BaseLoraxClass):
             return None
 
         # create dm device
-        dmdev = create_dm_dev("efiboot", disksize / 512, loopdev)
+        tablename = "efiboot%s" % (os.getpid(),)
+        dmdev = create_dm_dev(tablename, disksize / 512, loopdev)
 
         if not dmdev:
             remove_loop_dev(loopdev)