hash: Add support for arrays

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

Change-Id: I111511fcd2c1627011b47cf3593cc9d63d752c1a
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/meson.build b/test/meson.build
index ab788ff..1e15a0e 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -4,6 +4,7 @@
   'handle/copyable': [stdplus_dep, gtest_main_dep],
   'handle/managed': [stdplus_dep, gtest_main_dep],
   'hash': [stdplus_dep, gtest_main_dep],
+  'hash/array': [stdplus_dep, gtest_main_dep],
   'hash/tuple': [stdplus_dep, gtest_main_dep],
   'pinned': [stdplus_dep, gtest_main_dep],
   'raw': [stdplus_dep, gmock_dep, gtest_main_dep],