patman: add distutils based installer

To make it easier to use patman on other projects add a distutils style
installer. Now patman can be installed with

  cd u-boot/tools/patman && python setup.py install

There are also the usual distutils options for creating source/binary
distributions of patman.

Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Chris Packham <judge.packham@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/patman.py b/tools/patman/patman.py
index 6c6473e..e76fc42 100755
--- a/tools/patman/patman.py
+++ b/tools/patman/patman.py
@@ -14,14 +14,18 @@
 import unittest
 
 # Our modules
-import checkpatch
-import command
-import gitutil
-import patchstream
-import project
-import settings
-import terminal
-import test
+try:
+    from patman import checkpatch, command, gitutil, patchstream, \
+        project, settings, terminal, test
+except ImportError:
+    import checkpatch
+    import command
+    import gitutil
+    import patchstream
+    import project
+    import settings
+    import terminal
+    import test
 
 
 parser = OptionParser()