LLVM ERROR: inconsistency in registered CommandLine options

[geky]

At the moment the dual dependencies on llvm-sys causes a strange error with LLVM:

$ ./target/debug/silverfish               
: CommandLine Error: Option 'help-list' registered more than once!
LLVM ERROR: inconsistency in registered CommandLine options       

Some googling around shows this is an issue that can happen if libLLVM gets linked twice:
https://stackoverflow.com/questions/54273632/llvm-linking-commandline-error-option-help-list-registered-more-than-once-l

The dual dependencies against llvm-sys might be the issue? I'm not sure if there is a way to tell cargo to deduplicate the linking:

$ cargo tree
llvm-alt v0.5.0 (git+https://github.com/Others/llvm-rs.git#754fdf857f83e64d371a046dcb8fa3587a176cf8)     
├── cbox v0.3.0                                                                                          
│   └── libc v0.2.51 (*)                                                                                 
├── libc v0.2.51 (*)                                                                                     
└── llvm-sys v0.3.0 (git+https://github.com/Others/llvm-sys.rs#f4d6b7523e9c3e71a45aa8155f0ef0911689033a) 

llvm-sys v90.0.0    
└── libc v0.2.51 (*)

[Others]

Probably suggests that removing llvm-alt is the path forward for #11

[Others]

Potentially fixed when #18 is merged?