Add some c++17 headers to the list of known headers.

This CL updates cpplint.py to add some of the c++17 header files to the
list of known c++ headers. We're specifically using optional and variant
in the Tint project and would like to remove the NOLINT lines necessary
to keep the linter happy.

Bug: dawn:1379
Change-Id: I41cacd21e0742f992cdd6913b7f4def556b543c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3709241
Auto-Submit: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

cpplint.py

@@ -329,15 +329,19 @@ _CPP_HEADERS = frozenset([
     'vector.h',
     # 17.6.1.2 C++ library headers
     'algorithm',
+    'any',
     'array',
     'atomic',
     'bitset',
+    'charconv',
     'chrono',
     'codecvt',
     'complex',
     'condition_variable',
     'deque',
+    'execution',
     'exception',
+    'filesystem',
     'forward_list',
     'fstream',
     'functional',
@@ -354,9 +358,11 @@ _CPP_HEADERS = frozenset([
     'locale',
     'map',
     'memory',
+    'memory_resource',
     'mutex',
     'new',
     'numeric',
+    'optional',
     'ostream',
     'queue',
     'random',
@@ -381,6 +387,7 @@ _CPP_HEADERS = frozenset([
     'unordered_set',
     'utility',
     'valarray',
+    'variant',
     'vector',
     # 17.6.1.2 C++ headers for C library facilities
     'cassert',