This involved adding 'copy' to more generics than I hoped, but an
experiment with making it implicit showed that that way lies madness --
unless enforced, you will not remember to mark functions that don't
copy as not requiring copyable kind.
Issue #1177
This patch changes how to specify ABI and link name of a native module.
Before:
native "cdecl" mod llvm = "rustllvm" {...}
After:
#[abi = "cdecl"]
#[link_name = "rustllvm"]
native mod llvm {...}
The old optional syntax for ABI and link name is no longer supported.
Fixes issue #547
