Given that the Google-supplied headers for Android do not declare S_IEXEC and it is used by batch.c, you have either modified the code or are using a non-standard toolchain.
You are clearly distributing rsync (a "Covered Work") in object code form.
What toolchain are you using to compile the sources?
It is a requirement under GPLv3 to release the Corresponding Source which includes the toolchain, even if you have not modified the sources.
The "Corresponding Source" for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including scripts to
control those activities.