Bug 1632497 - Make YouCompleteMe clangd completer work. r=jgraham

We need to use the new Settings() API, instead of the deprecated
FlagsForFile. Though in practice we can just delegate to it and it works
out of the box.

Differential Revision: https://phabricator.services.mozilla.com/D72152

.ycm_extra_conf.py

@@ -32,6 +32,13 @@ def _is_likely_cpp_header(filename):
     cpp_file = filename[:-1] + 'cpp'
     return os.path.exists(cpp_file)
 
+
+def Settings(**kwargs):
+    if kwargs[ 'language' ] == 'cfamily':
+        return FlagsForFile(kwargs['filename'])
+    return {}
+
+
 def FlagsForFile(filename):
     output = subprocess.check_output([path, 'compileflags', filename])
     output = output.decode('utf-8')