[SLP]Correctly detect minnum/maxnum patterns for select/cmp operations on floats.
The patch enables detection of minnum/maxnum patterns for float point
instruction, represented as select/cmp. Also, enables better cost
estimation for integer min/max patterns since the compiler starts
to estimate the scalars separately.
Reviewers: nikic, RKSimon
Reviewed By: RKSimon
Pull Request: https://github.com/llvm/llvm-project/pull/98570