You've spotted an error in compilation logic.
OK, here's how you can resolve this issue.
$ export CFLAGS="-O2 -g"
$ rm src/libXNVCtrl/libXNVCtrl.a
$ cd src/libXNVCtrl/
$ cd ../..
Before running all these commands you must edit root Makefile and comment out (just add # in the very beginning) line 169: $(call quiet_cmd,STRIP_CMD) $@
The resulting binary should weigh approximately 3.5MB.