Add ow2_asm license

Added empty license for build time dependency - ow2_asm library

Bug: webrtc:9393
Change-Id: I1d43ad986cbb50a26d0f5c88f119383de6f7309a
Reviewed-on: https://webrtc-review.googlesource.com/83166
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23597}

tools_webrtc/libs/generate_licenses.py

@@ -50,6 +50,7 @@ LIB_TO_LICENSES_DICT = {
 
     # Compile time dependencies, no license needed:
     'yasm': [],
+    'ow2_asm': [],
 }
 
 SCRIPT_DIR = os.path.dirname(os.path.realpath(sys.argv[0]))