[test-suite] Fix for CFLAGS="-ffp-contract=on"

Renato,

I see that you were not on CC to the following email thread.
I would appreciate if you could provide some guidance on how to fix
the test-suite.

So, let's separate the FP_CONTRACT from the FAST_MATH problems, and solve them separately, in separate patches.

Agreed.

We may want to avoid some tests with -Ofast or -ffast-math, but we don't want to avoid them with -ffp-contract, at least not as a first attempt.

Agreed.

So, remove any trace of fp-contract from this patch and let's look at it from a fast-math perspective. Then we'll look at the fp problem in a separate patch, which should not be similar to this one as a first attempt, but something similar to what Sebastian did on his Polybench patch.

Out of the failing tests reported by the bot on aarch64 with the FP
Contract patch,
the Polybench should be fixed now, and there are 5 more tests failing:

- MultiSource/Applications/oggenc: 48326 LoC
I think this one we should avoid touching: it is way too large at 50K
lines of code...
Renato, do you agree to add "-ffp-contract=off" to the CFLAGS for oggenc?

The other 4 seem to be "fixable" the way we fixed Polybench:
- MultiSource/Benchmarks/MiBench/telecomm-FFT 288 LoC
- MultiSource/Benchmarks/VersaBench/beamformer 279 LoC
- SingleSource/Benchmarks/Linpack 586 LoC
- SingleSource/Benchmarks/Misc-C++/Large/sphereflake.cpp 224 LoC

I will submit separate patches for each of these 4.
Renato, do you agree that this is a reasonable way to fix the
test-suite when compiled with -ffp-contract=on?

Thanks,
Sebastian

- MultiSource/Benchmarks/MiBench/telecomm-FFT 288 LoC

https://reviews.llvm.org/D25924

- MultiSource/Benchmarks/VersaBench/beamformer 279 LoC

https://reviews.llvm.org/D25923

- SingleSource/Benchmarks/Linpack 586 LoC
- SingleSource/Benchmarks/Misc-C++/Large/sphereflake.cpp 224 LoC

These two are harder.