Update checklicenses to pass.

tools/checklicenses/checklicenses.py

Index: tools/checklicenses/checklicenses.py
diff --git a/tools/checklicenses/checklicenses.py b/tools/checklicenses/checklicenses.py
index 9dabfb2cc61a6c4d633b11272493fd863de96f9c..2ed79ff8cdb72f5b3443530f0f908b4b5ca74221 100755
--- a/tools/checklicenses/checklicenses.py
+++ b/tools/checklicenses/checklicenses.py
@@ -192,6 +192,9 @@ PATH_SPECIFIC_WHITELISTED_LICENSES = {
     'third_party/gles2_book': [
         'UNKNOWN',
     ],
+    'third_party/gles2_conform/GTF_ES': [
+        'UNKNOWN',
+    ],
     'third_party/gpsd/release-2.38/gps.h': [
         'UNKNOWN',
     ],
@@ -367,6 +370,9 @@ PATH_SPECIFIC_WHITELISTED_LICENSES = {
     'tools/gyp/test': [
         'UNKNOWN',
     ],
+    'tools/histograms': [
+        'UNKNOWN',
+    ],
     'tools/memory_watcher': [
         'UNKNOWN',
     ],
@@ -436,6 +442,11 @@ def main(options, args):
     filename, license = line.split(':', 1)
     filename = os.path.relpath(filename.strip(), options.base_directory)
 
+    # All files in the build output directory are generated one way or another.
+    # There's no need to check them.
+    if filename.startswith('out/') or filename.startswith('sconsbuild/'):
+      continue
+
     # For now we're just interested in the license.
     license = license.replace('*No copyright*', '').strip()