Check for CMAKE_TOOLCHAIN_FILE when creating cmake config

We don't do anything fancy anymore for non-cross builds
and when a specific CMAKE_TOOLCHAIN_FILE is specified.

boring-sys/build/config.rs

@@ -30,6 +30,7 @@ pub(crate) struct Env {
     pub(crate) debug: Option<OsString>,
     pub(crate) opt_level: Option<OsString>,
     pub(crate) android_ndk_home: Option<PathBuf>,
+    pub(crate) cmake_toolchain_file: Option<PathBuf>,
 }
 
 impl Config {
@@ -147,6 +148,7 @@ impl Env {
             debug: target_var("DEBUG"),
             opt_level: target_var("OPT_LEVEL"),
             android_ndk_home: target_var("ANDROID_NDK_HOME").map(Into::into),
+            cmake_toolchain_file: target_var("CMAKE_TOOLCHAIN_FILE").map(Into::into),
         }
     }
 }

boring-sys/build/main.rs

@@ -185,7 +185,14 @@ fn get_boringssl_cmake_config(config: &Config) -> cmake::Config {
     let src_path = get_boringssl_source_path(config);
     let mut boringssl_cmake = cmake::Config::new(src_path);
 
-    if config.host != config.target {
+    if config.host == config.target {
+        return boringssl_cmake;
+    }
+
+    if config.env.cmake_toolchain_file.is_some() {
+        return boringssl_cmake;
+    }
+
     // Add platform-specific parameters for cross-compilation.
     match &*config.target_os {
         "android" => {
@@ -286,7 +293,6 @@ fn get_boringssl_cmake_config(config: &Config) -> cmake::Config {
 
         _ => {}
     }
-    }
 
     boringssl_cmake
 }