[libfuzzer] support multiple seed_corpus directories.

testing/libfuzzer/archive_corpus.py

Index: testing/libfuzzer/archive_corpus.py
diff --git a/testing/libfuzzer/archive_corpus.py b/testing/libfuzzer/archive_corpus.py
index 5eb92b35410723777016a9ce051a6324324b47a4..9d3bf93ff2deb71d0361750a3ed3a259f5f60d84 100755
--- a/testing/libfuzzer/archive_corpus.py
+++ b/testing/libfuzzer/archive_corpus.py
@@ -19,16 +19,19 @@ import zipfile
 
 def main():
   parser = argparse.ArgumentParser(description="Generate fuzzer config.")
-  parser.add_argument('--corpus', required=True)
-  parser.add_argument('--output', required=True)
+  parser.add_argument('corpus_directories', metavar='corpus_dir', type=str,
+                      nargs='+')
+  parser.add_argument('--output', metavar='output_archive_name.zip',
+                      required=True)
   args = parser.parse_args()
 
   corpus_files = []
 
-  for (dirpath, _, filenames) in os.walk(args.corpus):
-    for filename in filenames:
-      full_filename = os.path.join(dirpath, filename)
-      corpus_files.append(full_filename)
+  for directory in args.corpus_directories:
+    for (dirpath, _, filenames) in os.walk(directory):
+      for filename in filenames:
+        full_filename = os.path.join(dirpath, filename)
+        corpus_files.append(full_filename)
 
   with zipfile.ZipFile(args.output, 'w') as z:
     # Turn warnings into errors to interrupt the build: crbug.com/653920.