patman: Split alias entries on arbitrary whitespace

Previously the first three words in a git-mailrc alias entry could only
be separated by spaces. git-send-email and Mutt both allow arbitrary
whitespace here.
Signed-off-by: NAdam Sampson <ats@offog.org>
Reviewed-by: NSimon Glass <sjg@chromium.org>

tools/patman/settings.py

@@ -263,7 +263,7 @@ def _ReadAliasFile(fname):
                 line = line.strip()
                 if not line or line.startswith('#'):
                     continue
-                words = line.split(' ', 2)
+                words = line.split(None, 2)
                 if len(words) < 3 or words[0] != 'alias':
                     if not bad_line:
                         bad_line = "%s:%d:Invalid line '%s'" % (fname, linenum,