I can't offer a solution, but maybe get you looking in the right area.
My best guess is that because of this:
make mrproper....(bad exit status: 2)
make prepare-all....(bad exit status: 2)
The remaining build process is trying to build on a tainted kernel source tree, leading to the later failure. I've never built snapapi, but an option may be to download the source archive for the kernel that you have (make sure it's the same one), extract to it's own build directory and run
Then point the snapapi build to your new kernel source tree and see if the build succeeds. I wouldn't recommend continuing to make install of snapapi this way, but would rather use it as a diagnosis to get a clearer view of where the build is actually being caused to fail, then fix the cause (rather than the symptom).