Revert "[msan] Check qsort input." and "[msan] Intercept qsort, qsort_r."

Temporarily revert the qsort changes because they fail to build on bots
that build with modules:

> error: thread-local storage is not supported for the current
> target (iossim)

http://green.lab.llvm.org/green/job/clang-stage2-Rthinlto/1820/console
http://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/4983/console

This reverts commit ddf897fc.
This reverts commit 07861e95.