clang format: use c++17

Change-Id: I3351cce6704a2553409ed2981e9ddb37046e34bf

.clang-format

@@ -105,6 +105,6 @@ SpacesInContainerLiterals: false
 SpacesInCStyleCastParentheses: false
 SpacesInParentheses: false
 SpacesInSquareBrackets: false
-Standard:        Cpp11
+Standard:        c++17
 TabWidth:        4
 UseTab:          Never