Revert "Speedup to_string and to_wstring for integers using stack buffer and SSO."

This reverts commit 7ce7110e6d964778141c0866488e154b1ce73d69, it was
causing sanitizer bot failures due to changing behavior of
std::to_string(). See https://reviews.llvm.org/D59178#1532023

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@362680 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed