Revert "Revert "Fast ART x86 interpreter""

This reverts commit 2d093a1213cc2f85b5e5e02782332657c479eb94.

Disable x86 mterp compilation on Mac host builds (but keep enabled
for all target builds).

Change-Id: Ie355279f166d2964a786646ee53f065b7e0f5ede
diff --git a/runtime/interpreter/mterp/x86/op_long_to_int.S b/runtime/interpreter/mterp/x86/op_long_to_int.S
new file mode 100644
index 0000000..1c39b96
--- /dev/null
+++ b/runtime/interpreter/mterp/x86/op_long_to_int.S
@@ -0,0 +1,2 @@
+/* we ignore the high word, making this equivalent to a 32-bit reg move */
+%include "x86/op_move.S"