Fix an issue in `gn analyze` when building all.

tools/mb/mb.py

 #!/usr/bin/env python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
@@ skipping 1266 matching lines @@
         raise
 
       outp = {}
       if 'status' in gn_outp:
         outp['status'] = gn_outp['status']
       if 'error' in gn_outp:
         outp['error'] = gn_outp['error']
       if 'invalid_targets' in gn_outp:
         outp['invalid_targets'] = gn_outp['invalid_targets']
       if 'compile_targets' in gn_outp:
-        outp['compile_targets'] = [
-          label.replace('//', '') for label in gn_outp['compile_targets']]
+        if 'all' in gn_outp['compile_targets']:
+          outp['compile_targets'] = ['all']
+        else:
+          outp['compile_targets'] = [
+              label.replace('//', '') for label in gn_outp['compile_targets']]
       if 'test_targets' in gn_outp:
         outp['test_targets'] = [
           labels_to_targets[label] for label in gn_outp['test_targets']]
 
       if self.args.verbose:
         self.Print()
         self.Print('analyze output:')
         self.PrintJSON(outp)
         self.Print()
 
@@ skipping 221 matching lines @@
   # Then check to see if the arg contains any metacharacters other than
   # double quotes; if it does, quote everything (including the double
   # quotes) for safety.
   if any(a in UNSAFE_FOR_CMD for a in arg):
     arg = ''.join('^' + a if a in ALL_META_CHARS else a for a in arg)
   return arg
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))