buildman: Move to absolute imports

At present buildman sets the python path on startup so that it can access
the libraries it needs. If we convert to use absolute imports this is not
necessary.

Move buildman to use absolute imports. Also adjust moveconfig.py too since
it uses some buildman modules and cannot work without this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/builder.py b/tools/buildman/builder.py
index 1b61e3a..b7f2c42 100644
--- a/tools/buildman/builder.py
+++ b/tools/buildman/builder.py
@@ -17,12 +17,12 @@
 import threading
 import time
 
-import builderthread
+from buildman import builderthread
+from buildman import toolchain
 import command
 import gitutil
 import terminal
 from terminal import Print
-import toolchain
 
 """
 Theory of Operation