Fix path env on cygwin when cross compiling from Windows

Cargo.lock

@@ -117,6 +117,7 @@ dependencies = [
  "rust-embed",
  "serial_test",
  "terminfo",
+ "unix_path",
  "widestring",
 ]
 
@@ -545,6 +546,21 @@ version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
 
+[[package]]
+name = "unix_path"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af8e291873ae77c4c8d9c9b34d0bee68a35b048fb39c263a5155e0e353783eaf"
+dependencies = [
+ "unix_str",
+]
+
+[[package]]
+name = "unix_str"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2ace0b4755d0a2959962769239d56267f8a024fef2d9b32666b3dcd0946b0906"
+
 [[package]]
 name = "version_check"
 version = "0.9.5"