remainder-ieee: Work around test failure on OSF/1.

remainder-ieee: Work around test failure on OSF/1.

* m4/remainder-ieee.m4: New file.
* m4/remainder.m4 (gl_FUNC_REMAINDER): If gl_FUNC_REMAINDER_IEEE is
present, test whether remainder works with a zero second argument.
Replace it if not.
* lib/math.in.h (remainder): Override if REPLACE_REMAINDER is 1.
* m4/math_h.m4 (gl_MATH_H_DEFAULTS): Initialize REPLACE_REMAINDER.
* modules/math (Makefile.am): Substitute REPLACE_REMAINDER.
* modules/remainder (configure.ac): Consider REPLACE_REMAINDER.
(Depends-on): Update dependencies.
* modules/remainder-ieee (Files): Add m4/remainder-ieee.m4.
(configure.ac): Invoke gl_FUNC_REMAINDER_IEEE.
* doc/posix-functions/remainder.texi: Mention the remainder-ieee module.