logl: Work around OSF/1 5.1 bug. * lib/math.in.h (logl): Override if REPLACE_LOGL is 1. * lib/logl.c (logl): If logf exists, use it and provide just the workaround. * m4/logl.m4 (gl_FUNC_LOGL_WORKS): New macro. (gl_FUNC_LOGL): Invoke it. Set REPLACE_LOGL. * m4/math_h.m4 (gl_MATH_H_DEFAULTS): Initialize REPLACE_LOGL. * modules/math (Makefile.am): Substitute REPLACE_LOGL. * modules/logl (configure.ac): Consider REPLACE_LOGL. (Depends-on): Update conditions. * doc/posix-functions/logl.texi: Mention the OSF/1 5.1 problem.

--- a/doc/posix-functions/logl.texi
+++ b/doc/posix-functions/logl.texi
@@ -20,6 +20,9 @@
 @item
 This function returns wrong results on some platforms:
 glibc 2.7 on Linux/SPARC64.
+@item
+This function returns a wrong value for a minus zero argument on some platforms:
+OSF/1 5.1.
 @end itemize
 
 Portability problems not fixed by Gnulib: