[patch] Update libstdc++ status docs, add C++17 status

[Jonathan Wakely]

This updates the C++11 and C++14/TS status tables, and adds a new
table for C++17 features.

Committed to trunk.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: patch.txt
Type: text/x-patch
Size: 12164 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/gcc-patches/attachments/20150501/68a2be79/attachment.bin>