Remove hex character number from wchar_t test

After r220894 (StringPrinter change) it is no longer emitted. Update the
test rather than considering it a bug as the new format is preferred.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@220914 91177308-0d34-0410-b5e6-96231b3b80d8
Also port the C string reading code in ValueObject over to using StringPrinter API

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@220917 91177308-0d34-0410-b5e6-96231b3b80d8
Remove #include <codecvt>.  It isn't supported on all compilers.

Also it wasn't being used anyway, so it appears to be a dead include.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@220921 91177308-0d34-0410-b5e6-96231b3b80d8
Merge remote-tracking branch 'upstream/master' into gold