cpp: Resolve an ambiguous overload in some tests

sqrt is defined for floats and long doubles in addition to doubles.
Add a cast (from int) to specify which one we want.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@776930 13f79535-47bb-0310-9956-ffa450edef68
2 files changed