[sanitizer] Fix wrong size of OFF_T on 32-bit platforms.

This broke pread/pwrite interceptors when building without
-D_FILE_OFFSET_BITS=64, and always on Android.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@174593 91177308-0d34-0410-b5e6-96231b3b80d8