Remove the async_cmds and sync_cmds from command.py

In bitbake/lib/bb/command.py::Command::__init__, we have the following
lines:

for attr in CommandsSync.__dict__:
    command = attr[:].lower()
    method = getattr(CommandsSync, attr)
    sync_cmds[command] = (method)

for attr in CommandsAsync.__dict__:
    command = attr[:].lower()
    method = getattr(CommandsAsync, attr)
    async_cmds[command] = (method)

The sync_cmds and async_cmds are defined as global dictionaries, but it
seems that we've never used them (I did a "grep -r async_cmds bitbake/",
, there is no result except the ones that I have removed), and I can't
find the history of it from "git log -p", I guess that they have been
replaced by the self.cmds_sync and self.cmds_async.

[YOCTO #1791]

(Bitbake rev: 24e99460800856035bb54a84c7aa33b3517436e9)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/command.py

@@ -31,10 +31,6 @@ Commands are queued in a CommandQueue
 import bb.event
 import bb.cooker
 
-async_cmds = {}
-sync_cmds = {}
-
-
 class CommandCompleted(bb.event.Event):
     pass
 
@@ -60,16 +56,6 @@ class Command:
         # FIXME Add lock for this
         self.currentAsyncCommand = None
 
-        for attr in CommandsSync.__dict__:
-            command = attr[:].lower()
-            method = getattr(CommandsSync, attr)
-            sync_cmds[command] = (method)
-
-        for attr in CommandsAsync.__dict__:
-            command = attr[:].lower()
-            method = getattr(CommandsAsync, attr)
-            async_cmds[command] = (method)
-
     def runCommand(self, commandline):
         try:
             command = commandline.pop(0)