<unordered_map> is not available on Android J-L.

Bug b/28006371

Change-Id: I7e06ebef092a7d3eef217f88e6fb6347c8d40ac1
Reviewed-on: https://swiftshader-review.googlesource.com/15149Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>