Revert "[asan] Make __cxa_demangle non-weak symbol on Android."

stlport doesn't include __cxa_demangle.

This reverts r201545.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@203601 91177308-0d34-0410-b5e6-96231b3b80d8