[sanitizer] Unconditionally write to target buffer in *sprintf interceptors.

This does not change the default behavior (check_printf in on by default in all tools).
With this change, check_printf flag only affects format string parsing.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208290 91177308-0d34-0410-b5e6-96231b3b80d8