Disable memory init file until further notice

It's support is currently too buggy in both Rust tests and Cargo.

src/librustc_trans/back/linker.rs

@@ -570,6 +570,8 @@ impl<'a> Linker for EmLinker<'a> {
             OptLevel::Size => "-Os",
             OptLevel::SizeMin => "-Oz"
         });
+        // Unusable until https://github.com/rust-lang/rust/issues/38454 is resolved
+        self.cmd.args(&["--memory-init-file", "0"]);
     }
 
     fn debuginfo(&mut self) {