The declarations of many functions in math_private.h are not required
since __MATHDECL and __MATHDECLX, in math.h, already provide the
declarations for these functions. This patch removes the declarations
from math_private.h. It also adds the inclusion of math.h to the files
which depended on the declaration of functions in math_private.h.
Tested for powerpc64le and s390x.
* sysdeps/generic/math_private.h: Remove declarations of
many functions that are already declared in math.h.
* sysdeps/ieee754/ldbl-128/e_logl.c: Include math.h to get the
declaration for __frexpl.
* sysdeps/ieee754/ldbl-128ibm/e_logl.c: Include math.h to get
the declarations for __scalbnl and fabsl.