Auto merge of #78 - mmatyas:arm_build2, r=metajack

Disable initial values set by `make`.

This fixes cross compilation issues, so it now builds correctly for both Android and ARM.
(See servo/servo#6537)

Part of servo/servo#6327.

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build.rs

@@ -8,7 +8,7 @@ use std::process::{Command, Stdio};
 fn main() {
     let out_dir = env::var("OUT_DIR").unwrap();
     let result = Command::new("make")
-        .args(&["-f", "makefile.cargo"])
+        .args(&["-R", "-f", "makefile.cargo"])
         .stdout(Stdio::inherit())
         .stderr(Stdio::inherit())
         .status()