Unbreak on i386/amd64 and update to 1.25.0-2018-02-19

• Stop using git to build as it is unmaintainable due to submodules, but more importantly because src/vendor is no longer bundled. Just fetch the source already generated that has all dependencies bundled. It may be a bit slower to get updates but is far more maintainable.
• Copy all patches to lang/rust-nightly/files since they may not always apply exactly between both versions.
• Add in patch for llvm-config getting -lexecinfo wrong, this is in review with LLVM at https://reviews.llvm.org/D42702.
• Bring in other random updates from lang/rust.