doc: Update doc regarding <ieee754.h>

[Bruno Haible]

Usually on glibc systems, there is an <ieee754.h> file available. But not so
on the cfarm105.cfarm.net machine (Debian, sparc64). Let me update the doc.


2023-06-25  Bruno Haible  <bruno@clisp.org>

        doc: Update doc regarding <ieee754.h>.
        * doc/glibc-headers/ieee754.texi: Mention that it's not present on
        glibc/sparc64 in 32-bit mode.

diff --git a/doc/glibc-headers/ieee754.texi b/doc/glibc-headers/ieee754.texi
index 1cc06ca600..66ecde3800 100644
--- a/doc/glibc-headers/ieee754.texi
+++ b/doc/glibc-headers/ieee754.texi
@@ -10,7 +10,7 @@
 @itemize
 @item
 This header file is missing on all non-glibc platforms:
-macOS 11.1, FreeBSD 13.0, NetBSD 9.0, OpenBSD 6.7, Minix 3.1.8, AIX 5.1, HP-UX 
11, IRIX 6.5, Solaris 11.4, Cygwin, mingw, MSVC 14, Android 9.0.
+glibc/sparc64 in 32-bit mode, macOS 11.1, FreeBSD 13.0, NetBSD 9.0, OpenBSD 
6.7, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.4, Cygwin, mingw, 
MSVC 14, Android 9.0.
 @end itemize
 
 Portability problems not fixed by Gnulib: