fixed canonicalisation of include path in windows (#35)

Author: l3utterfly

pqcrypto-internals/Cargo.toml

@@ -11,6 +11,7 @@ links = "pqcrypto_internals"
 
 [build-dependencies]
 cc = { version = "1.0", features = ["parallel"] }
+dunce = "1.0.2"
 
 [dependencies]
 getrandom = "0.2"

pqcrypto-internals/build.rs

@@ -1,10 +1,11 @@
 extern crate cc;
+extern crate dunce;
 
 use std::env;
 use std::path::Path;
 
 fn main() {
-    let includepath = Path::new("include").canonicalize().unwrap();
+    let includepath = dunce::canonicalize(Path::new("include")).unwrap();
     println!("cargo:includepath={}", includepath.to_str().unwrap());
 
     let cfiledir = Path::new("cfiles");