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/fpcmp.S b/runtime/interpreter/mterp/x86/fpcmp.S
new file mode 100644
index 0000000..2b98667
--- /dev/null
+++ b/runtime/interpreter/mterp/x86/fpcmp.S
@@ -0,0 +1,35 @@
+%default {"suff":"d","nanval":"pos"}
+/*
+ * Compare two floating-point values.  Puts 0, 1, or -1 into the
+ * destination register based on the results of the comparison.
+ *
+ * int compare(x, y) {
+ *     if (x == y) {
+ *         return 0;
+ *     } else if (x < y) {
+ *         return -1;
+ *     } else if (x > y) {
+ *         return 1;
+ *     } else {
+ *         return nanval ? 1 : -1;
+ *     }
+ * }
+ */
+    /* op vAA, vBB, vCC */
+    movzbl  3(rPC), %ecx                    # ecx<- CC
+    movzbl  2(rPC), %eax                    # eax<- BB
+    movs${suff} VREG_ADDRESS(%eax), %xmm0
+    xor     %eax, %eax
+    ucomis${suff} VREG_ADDRESS(%ecx), %xmm0
+    jp      .L${opcode}_nan_is_${nanval}
+    je      .L${opcode}_finish
+    jb      .L${opcode}_less
+.L${opcode}_nan_is_pos:
+    incl    %eax
+    jmp     .L${opcode}_finish
+.L${opcode}_nan_is_neg:
+.L${opcode}_less:
+    decl    %eax
+.L${opcode}_finish:
+    SET_VREG %eax rINST
+    ADVANCE_PC_FETCH_AND_GOTO_NEXT 2