ART: Avoid implicit conversion warning

Add NOLINT to experimental_flags.h, as the conversion is intended.

Bug: 32619234
Test: m
Change-Id: I1f7d2260a84c113b627e70240ae7ca22bdd1331f
diff --git a/runtime/experimental_flags.h b/runtime/experimental_flags.h
index 0471c96..b7f4037 100644
--- a/runtime/experimental_flags.h
+++ b/runtime/experimental_flags.h
@@ -33,7 +33,7 @@
   constexpr ExperimentalFlags(decltype(kNone) t)  // NOLINT, implicit
       : value_(static_cast<uint32_t>(t)) {}
 
-  constexpr operator decltype(kNone)() const {
+  constexpr operator decltype(kNone)() const {  // NOLINT, implicit
     return static_cast<decltype(kNone)>(value_);
   }