* lib/math.in.h (getpayloadf): New declaration.
* lib/getpayloadf.c: New file.
* m4/math_h.m4 (gl_MATH_H): Test whether getpayloadf is declared.
(gl_MATH_H_REQUIRE_DEFAULTS): Initialize GNULIB_GETPAYLOADF.
(gl_MATH_H_DEFAULTS): Initialize HAVE_GETPAYLOADF, REPLACE_GETPAYLOADF.
* modules/math (Makefile.am): Substitute GNULIB_GETPAYLOADF,
HAVE_GETPAYLOADF, REPLACE_GETPAYLOADF.
* modules/getpayloadf: New file.
* doc/posix-functions/getpayloadf.texi: Mention the new module and the
glibc bug.