* lib/math.in.h (sinhf): New declaration.
* lib/sinhf.c: New file.
* m4/sinhf.m4: New file.
* m4/math_h.m4 (gl_MATH_H): Test whether sinhf is declared.
(gl_MATH_H_DEFAULTS): Initialize GNULIB_SINHF, HAVE_SINHF.
* modules/math (Makefile.am): Substitute GNULIB_SINHF, HAVE_SINHF.
* modules/sinhf: New file.
* tests/test-math-c++.cc: Check the declaration of sinhf.
* doc/posix-functions/sinhf.texi: Mention the new module.