[wwwdocs,C++] Update notes on C++17 and C++2a support.

[wwwdocs,C++] Update notes on C++17 and C++2a support.

[Gerald Pfeifer]

Streamline these two sections, remove references to svn.html, note
the latter has landed by now.

Pushed.


Jonathan, Marek, Jason, it might be good if you could go through 
the page and see whether there are similar simplifications/updates.

Thanks,
Gerald

---
 htdocs/projects/cxx-status.html | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/htdocs/projects/cxx-status.html b/htdocs/projects/cxx-status.html
index dd3702dc..8d9dbce6 100644
--- a/htdocs/projects/cxx-status.html
+++ b/htdocs/projects/cxx-status.html
@@ -36,9 +36,7 @@
   <p>GCC has experimental support for the next revision of the C++
   standard, which is expected to be published in 2020.</p>
 
-  <p>C++2a features are available as part of "mainline" GCC
-    in the trunk of <a href="../svn.html">GCC's repository</a>
-    and will be available in GCC 8 and later. To enable C++2a
+  <p>C++2a features are available since GCC 8. To enable C++2a
       support, add the command-line parameter <code>-std=c++2a</code>
       to your <code>g++</code> command line. Or, to enable GNU
       extensions in addition to C++2a features,
@@ -462,9 +460,7 @@
   <a href="https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2017">the library documentation</a>.
   </p>
 
-  <p>C++17 features are available as part of "mainline" GCC
-    in the trunk of <a href="../svn.html">GCC's repository</a>
-    and in GCC 5 and later. To enable C++17
+  <p>C++17 features are available since GCC 5. To enable C++17
       support, add the command-line parameter <code>-std=c++17</code>
       to your <code>g++</code> command line. Or, to enable GNU
       extensions in addition to C++17 features,
-- 
2.24.1