[PATCH, wwwdocs] gcc-11/changes: C++11 is now required to build GCC

[David Malcolm]

This summarizes GCC 11's change in build requirements from C++98 to
C++11, for the release notes.  I've put it in the Caveats immediately
below the "The default mode for C++ is..." change hence the wording.

I've based it on the change to gcc/doc/install.texi in the
GCC source tree, which was 5329b59a2e13dabbe2038af0fe2e3cf5fc7f98ed
there.

Validates.

OK to commit?

---
 htdocs/gcc-11/changes.html | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/htdocs/gcc-11/changes.html b/htdocs/gcc-11/changes.html
index e2a32e51..e33abe44 100644
--- a/htdocs/gcc-11/changes.html
+++ b/htdocs/gcc-11/changes.html
@@ -35,6 +35,11 @@ a work-in-progress.</p>
       features with <code>-fno-new-ttp-matching</code>.
   </li>
 
+  <li>When building GCC itself, the host compiler must now support C++11,
+    rather than C++98.  In particular bootstrapping GCC 11 using an older
+    version of GCC requires a binary of GCC 4.8 or later, rather than of
+    GCC 3.4 or later as was the case for bootstrapping GCC 10.</li>
+
   <li>Naming and location of auxiliary and dump output files changed.
       If you compile multiple input files in a single command, if you
       enable Link Time Optimization, or if you use <code>-dumpbase</code>,
-- 
2.26.2