Here's how I'm able to build this.

Note that you have to follow the SDK instructions for installing a testsig.  
Try the "calculator" or other example in the SDK to make sure you can execute on the DSP.

0) Download and install the Hexagon SDK 3.3 (3.2 may also work)

1) Source the Hexagon SDK setup_sdk_env.sh script.

2) make tree VERBOSE=1 V=hexagon_Release_dynamic_toolv81_v60

3) make tree VERBOSE=1 V=android_Release

4) adb root ; adb remount

5) adb push android_Release/ship/graph_app /data

6) adb push hexagon_Release_dynamic_toolv81_v60/ship/libhexagon_nn_skel.so /system/vendor/lib/rfsa/adsp/

7) adb wait-for-device ; adb root ; adb remount     # (not sure if really necessary)

8) adb shell /data/graph_app --help for info

Example command line:
   adb shell /data/graph_app --height 299 --width 299 --depth 3 --elementsize 4 --perfdump 1 /data/keyboard_299.dat