Googletest export

Add missing explicit keyword for gmock_Impl constructor.

When switching to using GMOCK_PP in ACTION* macroses `explicit` keyword was
missed in gmock_Impl constructor causing ClangTidy warnings in ACTION_P macro.

PiperOrigin-RevId: 291159975
diff --git a/googlemock/include/gmock/gmock-actions.h b/googlemock/include/gmock/gmock-actions.h
index 8801179..e46bcaa 100644
--- a/googlemock/include/gmock/gmock-actions.h
+++ b/googlemock/include/gmock/gmock-actions.h
@@ -1426,7 +1426,7 @@
       typedef typename ::testing::internal::Function<F>::Result return_type;  \
       typedef                                                                 \
           typename ::testing::internal::Function<F>::ArgumentTuple args_type; \
-      gmock_Impl(GMOCK_ACTION_TYPE_GVALUE_PARAMS_(params))                    \
+      explicit gmock_Impl(GMOCK_ACTION_TYPE_GVALUE_PARAMS_(params))           \
           : GMOCK_ACTION_INIT_PARAMS_(params) {}                              \
       return_type Perform(const args_type& args) override {                   \
         return ::testing::internal::ActionHelper<return_type,                 \