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/src/hash/array.cpp b/src/hash/array.cpp
new file mode 100644
index 0000000..d736797
--- /dev/null
+++ b/src/hash/array.cpp
@@ -0,0 +1 @@
+#include <stdplus/hash/array.hpp>