fix bug in convert_array
add error and fix up bounds handling for array/vector conversion
change scoping scheme

this changes the "scope" scheme in loc2c to just use a static counter.
this is much simpler and also guarantees unique names in all
situations
add many more tests

now coverage is reasonably good for most files
loc2c.c still has low coverage (30%)
gdbjit-load.c is at 65%, so should be improved as well
the rest are all over 80%