A little closure towards translating spawn. We're about ready to do the upcall, except that rustc segfaults.

Started working on translating spawn. It correctly generates the task name in the case that it is not provided.

Added a couple of test cases for sending messages. One works as expected, the other succeeds unexpectedly.

stdlib: Modify union-find to guarantee that root nodes are always less than or equal to leaf nodes; add a "prune" method

This fixes compiling the fuzzer application.

On some platform (OS X), llvm needs macros like
__STDC_LIMIT_MACROS defined in order to work, which is
normally defined in llvm-config. This patch modifies
the config to use CFG_LLVM_ROOT's llvm-config if it
exists, which fixes the compile failures.

This depends on llvm's 131294.

After all that, give up on "complex" version of type_has_pointers and just manually inspect. Can't calculate property during interning.

Move the ty_item_table into ty::ctxt.items, move variant_info to ty, and start sketching the contains_pointer property on types.

rustc: Unify variables using a single type instead of keeping a list and doing it all at the end. This will give us better error messages.

And fix a the single screw-up in the source code it caught.

No functional change. Largely removed the native module/non-native module distinction from resolve.rs

and kill dead code.