Fix OS compatibility issues with building Clap on Windows so the build succeeds

[jamesray1]

Describe the bug

error[E0433]: failed to resolve. Could not findunixinos--> C:\Users\ChosunOne\.cargo\registry\src\github.com-1ecc6299db9ec823\clap-2.31.2\src\app\parser.rs:7:14 | 7 | use std::os::unix::ffi::OsStrExt; | ^^^^ Could not findunixinos``

From https://gitter.im/Drops-of-Diamond/Development?at=5aed4e101eddba3d04d3ddb2.

To Reproduce
Steps to reproduce the behavior:

1. Run cargo make build on a Windows OS

Expected behavior
The project should build.

Desktop (please complete the following information):

• OS: Windows 10 64-bit

[ChosunOne]

A workaround is to change the parser.rs file line 7 to:
use std::os::windows::ffi::OsStrExt;
and add the line:
use osstringext::OsStrExt3;
after it. This will fix the build errors but will leave you with a nonstandard version of clap.

[jamesray1]

So that we don't have to configure this manually, try:

#[cfg(not(target_os = "windows"))]
use std::os::unix::ffi::OsStrExt;
#[cfg(target_os = "windows")]
use osstringext::OsStrExt3;

From https://github.com/kbknapp/clap-rs/pull/1190/files#diff-3519f1369b63436798d9d7841c7940e2R672.

[jamesray1]

Alternatively we could use https://github.com/kbknapp/clap-rs#optional-dependencies--features:

[dependencies.clap]
version = "2.31"
default-features = false

# Cherry-pick the features you'd like to use
features = [ "suggestions", "vec_map" ]

[ChosunOne]

The alternative method still doesn't build, but reintroducing the target checks in parser.rs of clap fixes the issue. We should raise an issue with clap about this.

[stevepentland]

Thanks for pointing this one out! It seems a case that has been both missed during my changes and before that time also. I have fixed the issue and tested using a copy of your specific project also and can report success. Once the PR merges you should be good to update and go.