tools, scripts: refactor error-out statements of Python scripts

In Python, sys.exit() function can also take an object other
than an integer.

If an integer is given to the argument, Python exits with the return
code of it.  If a non-integer argument is given, Python outputs it
to stderr and exits with the return code of 1.

That means,

    print >> sys.stderr, "Blah Blah"
    sys.exit(1)

is equivalent to

    sys.exit("Blah Blah")

The latter is a useful shorthand.

Note:
Some error messages in Buildman and Patman were output to stdout.
But they should go to stderr.  They are also fixed by this commit.
This is a nice side effect.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>

tools/buildman/control.py

@@ -110,15 +110,13 @@ def DoBuildman(options, args):
             if count is None:
                 str = ("Branch '%s' not found or has no upstream" %
                        options.branch)
-                print col.Color(col.RED, str)
-                sys.exit(1)
+                sys.exit(col.Color(col.RED, str))
             count += 1   # Build upstream commit also
 
     if not count:
         str = ("No commits found to process in branch '%s': "
                "set branch's upstream or use -c flag" % options.branch)
-        print col.Color(col.RED, str)
-        sys.exit(1)
+        sys.exit(col.Color(col.RED, str))
 
     # Work out what subset of the boards we are building
     board_file = os.path.join(options.git, 'boards.cfg')
@@ -127,16 +125,14 @@ def DoBuildman(options, args):
         status = subprocess.call([os.path.join(options.git,
                                                'tools/genboardscfg.py')])
         if status != 0:
-            print >> sys.stderr, "Failed to generate boards.cfg"
-            sys.exit(1)
+            sys.exit("Failed to generate boards.cfg")
 
     boards = board.Boards()
     boards.ReadBoards(os.path.join(options.git, 'boards.cfg'))
     why_selected = boards.SelectBoards(args)
     selected = boards.GetSelected()
     if not len(selected):
-        print col.Color(col.RED, 'No matching boards found')
-        sys.exit(1)
+        sys.exit(col.Color(col.RED, 'No matching boards found'))
 
     # Read the metadata from the commits. First look at the upstream commit,
     # then the ones in the branch. We would like to do something like
@@ -182,8 +178,7 @@ def DoBuildman(options, args):
     gnu_make = command.Output(os.path.join(options.git,
                                            'scripts/show-gnu-make')).rstrip()
     if not gnu_make:
-        print >> sys.stderr, 'GNU Make not found'
-        sys.exit(1)
+        sys.exit('GNU Make not found')
 
     # Create a new builder with the selected options
     if options.branch: