Attempt to fix 64-bit MinGW windows

Author: alexcrichton

build.rs

@@ -21,8 +21,10 @@ fn main() {
 
     if target.starts_with("x86_64") {
         cfg.file(if msvc {"src/arch/x86_64.asm"} else {"src/arch/x86_64.S"});
+        cfg.define("X86_64", None);
     } else if target.contains("i686") {
         cfg.file(if msvc {"src/arch/i686.asm"} else {"src/arch/i686.S"});
+        cfg.define("X86", None);
     } else {
         panic!("\n\nusing currently unsupported target triple with \
                 stacker: {}\n\n", target);

src/arch/asm.h

@@ -1,4 +1,4 @@
-#if defined(APPLE) || defined(WINDOWS)
+#if defined(APPLE) || (defined(WINDOWS) && defined(X86))
 #define GLOBAL(name) .globl _ ## name; _ ## name
 #else
 #define GLOBAL(name) .globl name; name