* reworked amd64/_fpmath.h and arm64/_fpmath.h to support 128-bit long
doubles.
* improved tests to cover long double cases
* made modfl an alias for LP32
Tests pass on x86, x86_64, arm, arm64 and mips.
Bug: 12921273
Change-Id: Ibe39acde57972447a8950fa45b1e702acc68ebeb
Factored out common declarations to include/fenv.h and pushed
the implementation to .c files.
Bug: 11050744
Change-Id: I446b13cc4bc599d328343a8d392b07de280f6304