Remove ancient __signbit inlines
Remove __signbit inlines from mathinline.h. Math.h already uses
the builtin when supported, so additional inlines are only used
on pre 4.0 GCCs. Similarly remove ancient copysign and fabs
inlines.
* sysdeps/alpha/fpu/bits/mathinline.h: Delete file.
* sysdeps/ia64/fpu/bits/mathinline.h: Delete file.
* sysdeps/m68k/coldfire/fpu/bits/mathinline.h: Delete file.
* sysdeps/m68k/m680x0/fpu/bits/mathinline.h: (__signbitf): Remove.
(__signbit): Remove.
(__signbitl): Remove.
* sysdeps/powerpc/bits/mathinline.h (__signbitf): Remove.
(__signbit): Remove.
(__signbitl): Remove.
* sysdeps/s390/fpu/bits/mathinline.h: (__signbitf): Remove.
(__signbit): Remove.
(__signbitl): Remove
* sysdeps/sparc/fpu/bits/mathinline.h (__signbitf): Remove.
(__signbit): Remove.
(__signbitl): Remove.
* sysdeps/tile/bits/mathinline.h: Delete file.
* sysdeps/x86/fpu/bits/mathinline.h (__signbitf): Remove.
(__signbit): Remove.
(__signbitl): Remove.