[clang-cl] Parse /await:strict, new in MSVC 16.10

Author: zmodem

clang/include/clang/Driver/Options.td

@@ -6200,6 +6200,7 @@ def _SLASH_Zo_ : CLIgnoredFlag<"Zo-">;
 // Unsupported:
 
 def _SLASH_await : CLFlag<"await">;
+def _SLASH_await_COLON : CLJoined<"await:">;
 def _SLASH_constexpr : CLJoined<"constexpr:">;
 def _SLASH_AI : CLJoinedOrSeparate<"AI">;
 def _SLASH_Bt : CLFlag<"Bt">;

clang/test/Driver/cl-options.c

@@ -420,6 +420,7 @@
 // (/Zs is for syntax-only)
 // RUN: %clang_cl /Zs \
 // RUN:     /await \
+// RUN:     /await:strict \
 // RUN:     /constexpr:depth1000 /constexpr:backtrace1000 /constexpr:steps1000 \
 // RUN:     /AIfoo \
 // RUN:     /AI foo_does_not_exist \