AdvancedIncSubtensor1.c_code

Fixes #1763
(or more accurately it will when it is ok)

Replaces closed pull request #2286.
This method content seem to duplicate much of what is in gof/cutils.py. This method do not need to be in this class and do not need the self attrbute. Can you move it to cutils.py and make compile_cutils() call it instead of duplicating the code?