Added some missing issues to the c++1y status page, and put in hyperlinks for the papers.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188387 91177308-0d34-0410-b5e6-96231b3b80d8
Fix signed/unsigned warnings when building libc++ in C++14 mode

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188395 91177308-0d34-0410-b5e6-96231b3b80d8
Xing Xue:  port to IBM XLC++/AIX.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188396 91177308-0d34-0410-b5e6-96231b3b80d8
Relax complete-type check for functions and function pointers to allow void return type.  This bug was exposed by Eli Friedman's commit to clang r188324.  Anywhere this version of clang ships, this libc++ fix must follow.  However this fix is compatible with previous clangs, and so this libc++ doesn't need to wait for this clang.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188413 91177308-0d34-0410-b5e6-96231b3b80d8