tools/licenses.py: Ignore out/ directories that use out as a prefix.

E.g. I use out-gn/, and for me this change makes licenses.py run in 1.5
seconds rather than 3 seconds.

Our .gitignore ignores all top-level out* directories, so this script
should do the same.

Bug: None
Change-Id: I78cd1fea4c23d4990d52d2d521a41fe2267a2be6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2269317Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#783011}

tools/licenses.py

@@ -104,9 +104,7 @@ PRUNE_PATHS = set([
 
 # Directories we don't scan through.
 VCS_METADATA_DIRS = ('.svn', '.git')
-PRUNE_DIRS = (VCS_METADATA_DIRS +
-              ('out', 'Debug', 'Release',  # build files
-               'layout_tests'))            # lots of subdirs
+PRUNE_DIRS = VCS_METADATA_DIRS + ('layout_tests', )  # lots of subdirs
 
 # A third_party directory can define this file, containing a list of
 # subdirectories to process in addition to itself. Intended for directories
@@ -488,7 +486,8 @@ def FindThirdPartyDirs(prune_paths, root):
   for path, dirs, files in os.walk(root):
     path = path[len(root) + 1:]  # Pretty up the path.
 
-    if path in prune_paths:
+    # .gitignore ignores /out*/, so do the same here.
+    if path in prune_paths or path.startswith('out'):
       dirs[:] = []
       continue