Split <string.h> out of <cstring>.

Also fix the overload set for the five functions whose signatures change in the
case where we can fix it. This is already covered by existing tests for the
affected systems.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@249929 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed