nettle-sys: add llvm to build-deps
Without this change, we see (non-fatal) warnings like this during the build:
```
[nettle-sys 2.0.4] cargo:warning=couldn't execute `llvm-config --prefix` (error: No such file or directory (os error 2))
[nettle-sys 2.0.4] cargo:warning=set the LLVM_CONFIG_PATH environment variable to a valid `llvm-config` executable
[nettle-sys 2.0.4] Failed to run rustfmt: which wasn't enabled, and no rustfmt binary specified (non-fatal, continuing)
warning: couldn't execute `llvm-config --prefix` (error: No such file or directory (os error 2))
warning: set the LLVM_CONFIG_PATH environment variable to a valid `llvm-config` executable
```
We might want to add this to the dependencies for the library as well,
I'm not sure.
Daniel Kahn Gillmor
4 years ago