Added special cases to comments for asin.go and fabs.go.
Added Trunc() to floor.go and floor_386.s.  Fixed formatting
error in hypot_386.s  Added new functions Acosh, Asinh,
Atanh, Copysign, Erf, Erfc, Expm1, and Log1p.  Added
386 FPU version of Fmod.  Added tests, benchmarks, and
precision to expected results in all_test.go.  Edited
makefile so it all compiles.

R=rsc
CC=golang-dev
https://golang.org/cl/195052