libstdc++: Fix some -Wunused warnings in tests

libstdc++-v3/ChangeLog:

	* include/ext/pb_ds/detail/type_utils.hpp (PB_DS_STATIC_ASSERT):
	Add unused attribute to avoid -Wunused-local-typedef warnings.
	* testsuite/17_intro/tag_type_explicit_ctor.cc: Add pragma to
	ignore -Wunused-variable warnings

libstdc++-v3/include/ext/pb_ds/detail/type_utils.hpp

@@ -152,7 +152,8 @@ namespace __gnu_pbds
     };
 
 #define PB_DS_STATIC_ASSERT(UNIQUE, E)  \
-    typedef __gnu_pbds::detail::__static_assert_dumclass<sizeof(__gnu_pbds::detail::__static_assert<bool(E)>)> UNIQUE##__static_assert_type
+    typedef __gnu_pbds::detail::__static_assert_dumclass<sizeof(__gnu_pbds::detail::__static_assert<bool(E)>)> \
+      UNIQUE##__static_assert_type __attribute__((__unused__))
 
 #endif
 

libstdc++-v3/testsuite/17_intro/tag_type_explicit_ctor.cc

@@ -34,6 +34,8 @@ void f5(std::try_to_lock_t);
 void f6(std::adopt_lock_t);
 #endif
 
+#pragma GCC diagnostic ignored "-Wunused-variable"
+
 int main()
 {
   std::nothrow_t v1;