The dEQP tests for arccos/arcsin/arctan were failing due to
the precision of the arcsin/arccos/arctan approximation being
too low. It is possible to significantly improve this precision
with a few more terms, which is done here.

All arccos/arcsin/arctan dEQP tests pass.

Change-Id: I612551b48bdab03b81b2e72ddb8cd7f8502231c5
Reviewed-on: https://swiftshader-review.googlesource.com/13568Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>