hash: Add support for tuples

There is now builtin support for stdplus::hash<> and
stdplus::hashMulti(...) hashing std::tuple containers.

Change-Id: I0e0983c04d54302f00c811e5de0d949accee03d7
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/include/meson.build b/include/meson.build
index 358bc32..fc304f3 100644
--- a/include/meson.build
+++ b/include/meson.build
@@ -7,6 +7,7 @@
   'stdplus/handle/copyable.hpp',
   'stdplus/handle/managed.hpp',
   'stdplus/hash.hpp',
+  'stdplus/hash/tuple.hpp',
   'stdplus/pinned.hpp',
   'stdplus/raw.hpp',
   'stdplus/signal.hpp',