Use MesaLink header files bundled with the crate

Point to a MesaLink fork with the changes until they are published.

Author: sagebind

curl-sys/Cargo.toml

@@ -24,7 +24,9 @@ libc = "0.2.2"
 libnghttp2-sys = { optional = true, version = "0.1" }
 
 [dependencies.mesalink]
-version = "1.0.0-cratesio"
+version = "1.1.0-beta"
+git = "https://github.com/sagebind/mesalink"
+branch = "cargo-c-headers"
 optional = true
 default-features = false
 features = ["client_apis", "error_strings", "tls13", "aesgcm", "chachapoly", "x25519", "ecdh", "ecdsa", "verifier"]

curl-sys/build.rs

@@ -215,11 +215,16 @@ fn main() {
     // features, make sure we only compile one vtls.
     if cfg!(feature = "mesalink") {
         cfg.define("USE_MESALINK", None)
-            .include("include/mesalink")
             .file("curl/lib/vtls/mesalink.c");
 
+        if let Some(path) = env::var_os("DEP_MESALINK_INCLUDE") {
+            cfg.include(path);
+        }
+
         if windows {
             cfg.define("HAVE_WINDOWS", None);
+        } else {
+            cfg.define("HAVE_UNIX", None);
         }
     } else if cfg!(feature = "ssl") {
         if windows {