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