Revert "Revert "ART: Mterp for arm64""

Looks like some of our assemblers disagree on valid arm64 assembly syntax
Force use of clang for art runtime.  In a subsequent CL, will use form
that both gcc and clang accept.

This reverts commit 43f3fb960bce978df699c8a68a972be2a0d0d221.

Change-Id: Ice83072171ab502c43d492e2238b446c4814ea67
diff --git a/runtime/interpreter/mterp/arm64/shiftWide2addr.S b/runtime/interpreter/mterp/arm64/shiftWide2addr.S
new file mode 100644
index 0000000..77d104a
--- /dev/null
+++ b/runtime/interpreter/mterp/arm64/shiftWide2addr.S
@@ -0,0 +1,16 @@
+%default {"opcode":"lsl"}
+    /*
+     * Generic 64-bit shift operation.
+     */
+    /* binop/2addr vA, vB */
+    lsr     w1, wINST, #12              // w1<- B
+    ubfx    w2, wINST, #8, #4           // w2<- A
+    GET_VREG w1, w1                     // x1<- vB
+    GET_VREG_WIDE x0, w2                // x0<- vA
+    FETCH_ADVANCE_INST 1                // advance rPC, load rINST
+    and     x1, x1, #63                 // Mask low 6 bits.
+    $opcode x0, x0, x1
+    GET_INST_OPCODE ip                  // extract opcode from rINST
+    SET_VREG_WIDE x0, w2               // vAA<- result
+    GOTO_OPCODE ip                      // jump to next instruction
+    /* 10-13 instructions */