[Tests] Split float test into float and doubles

As I was waiting for the test suite to complete at 99% I noticed this
test taking quite a bit of time. Since it's easy to split I just went
ahead and did so.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@358792 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed