how to use dmd.lexer.Lexer

[jonatjano]

Hello,
I'm trying to write a script which parse a c header and then 
ouput basic bindings for multiple languages.

I read from the forum some times ago that the D compiler could be 
used as a library and found [the lexer page in the 
documentation](https://dlang.org/library/dmd/lexer/lexer.html)

but `import dmd.lexer: Lexer` fails with the following error :
```
modlibBinder.d(3): Error: unable to read module `lexer`
modlibBinder.d(3):        Expected 'dmd/lexer.d' or 
'dmd/lexer/package.d' in one of the following import paths:
import path[0] = .
import path[1] = /usr/include/dmd/phobos
import path[2] = /usr/include/dmd/druntime/import
Failed: ["/usr/bin/dmd", "-v", "-o-", "modlibBinder.d", "-I."]
```

What are the steps to take to be able to call the lexer (and 
maybe also the parser) over a C header file ?