correct fma has to ensure 'no intermediate overflow'
This is done in the case of signed integers by transtyping to unsigned type and back
using multiplies correct the unsigned short overflow problems with fnma and fnms
add missing cases to handle promotion + signed overflow correctly in fma/fms/fnms/fnma
remove unused typedefs in correct_fma tests
clean up correct_fma
Merge pull request #847 from jtlap/integer_correct_fma

Integer correct fma