Add 'merge' command to conv_linker_config

'merge' command can merge multiple configurations.
It just delegates protobuf's msg.MergeFrom(other_msg).

  usage: conv_linker_config merge -o out.pb -i a.pb -i b.pb ...

out.pb will have all keys from multiple inputs.

Bug: 181093750
Test: m
Test: MicrodroidTestCase
Change-Id: Ibf715aa0bcc1e5c82c85a9af8fe7dca8d6ab68ad

scripts/conv_linker_config.py

@@ -78,6 +78,14 @@ def Append(args):
   with open(args.output, 'wb') as f:
     f.write(pb.SerializeToString())
 
+def Merge(args):
+  pb = linker_config_pb2.LinkerConfig()
+  for other in args.input:
+    with open(other, 'rb') as f:
+      pb.MergeFromString(f.read())
+
+  with open(args.out, 'wb') as f:
+    f.write(pb.SerializeToString())
 
 def GetArgParser():
   parser = argparse.ArgumentParser()
@@ -161,6 +169,22 @@ def GetArgParser():
       help='Values of the libraries to append. If there are more than one it should be separated by empty space')
   append.set_defaults(func=Append)
 
+  append = subparsers.add_parser(
+      'merge', help='Merge configurations')
+  append.add_argument(
+      '-o',
+      '--out',
+      required=True,
+      type=str,
+      help='Ouptut linker configuration file to write in protobuf.')
+  append.add_argument(
+      '-i',
+      '--input',
+      nargs='+',
+      type=str,
+      help='Linker configuration files to merge.')
+  append.set_defaults(func=Merge)
+
   return parser