atanh, atanhf, atanhl): Add prototypes.
* mingwex/Makefile.in (MATH_OBJS): Add objects for above to list.
(MATH_DISTFILES): Add sources for above and fastmath.h to list.
Specify dependency on fastmath.h for new objects.
* mingwex/math/fastmath.h: New file.
* mingwex/math/ashinh.c: New file.
* mingwex/math/asinhf.c: New file.
* mingwex/math/asinhl.c: New file.
* mingwex/math/acosh.c: New file.
* mingwex/math/acoshf.c: New file.
* mingwex/math/acoshl.c: New file.
* mingwex/math/atanh.c: New file.
* mingwex/math/atanhf.c: New file.
* mingwex/math/atanhl.c: New file.