Add build.rs to make CI happy.

Author: Berrysoft

CHANGELOG.md

@@ -3,6 +3,9 @@
 - Add VxWorks support
   [#105](https://github.com/lambda-fairy/rust-errno/pull/105)
 
+- Add cygwin support
+  [#106](https://github.com/lambda-fairy/rust-errno/pull/106)
+
 # [0.3.10] - 2024-11-29
 
 - Update to windows-sys 0.59

Cargo.toml

@@ -17,10 +17,7 @@ libc = { version = "0.2", default-features = false }
 
 [target.'cfg(windows)'.dependencies.windows-sys]
 version = ">=0.52, <=0.59"
-features = [
-  "Win32_Foundation",
-  "Win32_System_Diagnostics_Debug",
-]
+features = ["Win32_Foundation", "Win32_System_Diagnostics_Debug"]
 
 [target.'cfg(target_os="wasi")'.dependencies]
 libc = { version = "0.2", default-features = false }
@@ -31,3 +28,6 @@ libc = { version = "0.2", default-features = false }
 [features]
 default = ["std"]
 std = ["libc/std"]
+
+[patch.'crates-io']
+libc = { path = "../libc" }

build.rs

@@ -0,0 +1,4 @@
+fn main() {
+    // Cygwin target, added in 1.86
+    println!("cargo:rustc-check-cfg=cfg(target_os, values(\"cygwin\"))");
+}