Avoid doing the internal binding of top-level symbols in the parser,
leaving that work to be done in a post-processing step. For builtins,
this lets us do a reference-aware bind step (block_bind_incremental)
*after* generating builtins/0.
Libraries are a bit trickier since they may be bound multiple times, so
instead of thinking through the implications I added (block_bind_self)
to resolve all internal symbols immediately.
Remove the special code which loads ~/.jq in builtin.c, and instead glue
an optional include which points to the same file onto the main program
in linker.c.
Fixes a minor bug where errors in ~/.jq would be labelled <builtin>.
Only the second and subsequent path components were being checked, which
I guess is theoretically security-relevant.
There's no apparent point to reconstructing the path after splitting it
by adding /s back in, either.
"Module path must be a string" is not a useful error message when the
reason the module path isn't a string is because the string it was got
replaced with an invalid with an error message for some other reason.
Also fixes a few memory leaks on early exits.