Enable logwrapper functionality on user builds

When an app is debuggable, check whether a script called "wrap.sh" exists
in the app's native library directory. If so, start the app using the
invoke-with functionality over the script. Weaken the invoke-with check
on the zygote side to allow the functionality for debuggable apps.

The goal of the functionality is to make malloc debug, strace and other
similar tools available for NDK based application developers.

Bug: 33668201
Test: manual - debug malloc can be enabled using the new feature
Change-Id: Ia4bec0854cf4dc08446f1671494200f54ef366ee