Rebuild std libraries on compile

[avelure]

I was lazy and didn't clean the build folder when compiling.
I then noticed that it seems like the build system doesn't detect that it needs to rebuild the standard libraries when the version of NVC changes, so you get an error later when you elaborate.

[nickg]

I tried this a few times in the past but never managed to get something that worked well. Maybe there could be a check that's hooked into make install.