Rust 1.39

[Chuck Musser]

Well, I got 1.39.0 to compile, but it might be that useful as an end 
product. This based on a fork of the "boostrap"repository: 
https://github.com/cmusser/rust-bootstrap-dragonfly. It has the 
following caveats:

- master only. Both the resulting language tools (rustc, etc) and the 
binaries compiled with them only work on a system running master. I 
tried them on a 5.6 system and they require a libc that is not present, 
which I guess isn't surprising.

- In order for rustc to work, I had to set LD_LIBRARY_PATH to the "lib" 
subdirectory of the build products directory (the directory you specify 
as an argument to build.sh). This directory contains shared libraries 
whose names have long suffixes. I'm not sure where these live on a 
"production" system.

- This is actually one version behind the current one, which is now 
1.40.

At any rate, I had to create a couple of patches (one for the 
__errno_location() in libc, the other in the openssl-sys crate, to 
specify the ssl library directory). Also, one of the existing patches, 
to a part of LLVM had to be modified so that the proper name of a field 
in the statvfs structure was used. I'm not sure how much of this stuff 
is correct or can be incorporated into a more official build, but it's 
there for anyone who wants to look around.

Chuck