Simplify delta calculation in TestTimer.cpp
Simplify delta calculation in TestTimer.cpp

For standard libraries that only provide float overloads for abs/std::abs,
this is necessary.

Also, IMHO, doing this instead of playing with fire using float casts and
whatnot seems to be the more sane approach.

Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble