Fix OpenBSD 4.0 <float.h> handling of long double. * m4/float_h.m4 (gl_FLOAT_H): Also claim OpenBSD is broken. * lib/float.in.h [__OpenBSD__]: Add fixes for OpenBSD. * doc/headers/float.texi (float.h): Document OpenBSD bug. Signed-off-by: Eric Blake <ebb9@byu.net>