MSVC generator hack should be only applied to MSVC

Author: msoxzw

boring-sys/build.rs

@@ -98,7 +98,7 @@ fn get_ios_sdk_name() -> &'static str {
 /// so adjust library location based on platform and build target.
 /// See issue: https://github.com/alexcrichton/cmake-rs/issues/18
 fn get_boringssl_platform_output_path() -> String {
-    if cfg!(windows) {
+    if cfg!(target_env = "msvc") {
         // Code under this branch should match the logic in cmake-rs
         let debug_env_var = std::env::var("DEBUG").expect("DEBUG variable not defined in env");