Backports to gcc-6-branch

Hi! I've backported following 8 patches from gcc-8-branch to gcc-6-branch, bootstrapped/regtested and committed to gcc-6-branch. Jakub 2018-10-12 Jakub Jelinek Backported from mainline 2018-07-16 Jakub Jelinek PR c++/3698 PR c++/86208 * cp-g

[committed] Backports to gcc-6-branch

Hi! I've committed over 3 dozens backports to the 6.x branch, after bootstrapping/regtesting them on x86_64-linux and i686-linux. Jakub 2017-05-05 Jakub Jelinek Backported from mainline 2017-02-16 Jakub Jelinek PR c++/79512 * c-parser.c (c_parser_om