setprop log.redirect-stdio true redirects only output generated by java code, but not the native code. This fact is described on developer.android.com in following way:
By default, the Android system sends stdout and stderr (System.out and System.err) output to /dev/null. In processes that run the Dalvik VM, you can have the system write a copy of the output to the log file.
To get output from the native code, I really liked this solution