Use feature instead of arch

Author: Rob Tsuk

Cargo.toml

@@ -11,5 +11,5 @@ build = "build.rs"
 [features]
 sse = []
 
-[target.'cfg(target_arch = "x86")'.build-dependencies]
+[target.'cfg(target_feature = "sse")'.build-dependencies]
 gcc = "0.3"

build.rs

@@ -1,8 +1,8 @@
-#[cfg(target_arch = "x86")]
+#[cfg(feature="sse")]
 extern crate gcc;
 
 fn main() {
-    #[cfg(target_arch = "x86")]
+    #[cfg(feature="sse")]
     gcc::Build::new()
         .file("src/accumulate.c")
         .flag("-march=native")