Added exception handling for ImportError
diff --git a/src/boringssl/gen_build_yaml.py b/src/boringssl/gen_build_yaml.py
index 4ce7232..0d4ad0b 100755
--- a/src/boringssl/gen_build_yaml.py
+++ b/src/boringssl/gen_build_yaml.py
@@ -38,7 +38,11 @@
     '../../third_party/boringssl'))
 sys.path.append(os.path.join(boring_ssl_root, 'util'))
 
-import generate_build_files
+try:
+  import generate_build_files
+except ImportError:
+  print yaml.dump({})
+  sys.exit()
 
 def map_dir(filename):
   if filename[0:4] == 'src/':