Failures in dEQP using SwiftShader with LLVM 7.0 were caused by unsafe
floating point math optimizations, which are more aggressive than with
LLVM 3.0.

Bug b/115344057

Change-Id: Idf564d0193efba37cd1192a188b18a5f8b4ed4f7
Reviewed-on: https://swiftshader-review.googlesource.com/20708Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Shannon Woods <shannonwoods@google.com>