Fix issues with Arm's use of embedded constant pools

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index cb52541b5690ffbeb4e36ad282d7282a1429be57..15c531960f337ac094ebd24c08bcdac8a34c2535 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -704,6 +704,9 @@ class Assembler : public AssemblerBase {
   // possible to align the pc offset to a multiple
   // of m, where m must be a power of 2.
   void Align(int m);
+  // Insert the smallest number of zero bytes possible to align the pc offset
+  // to a mulitple of m. m must be a power of 2 (>= 2).
+  void DataAlign(int m);
   void Nop(int bytes = 1);
   // Aligns code to something that's optimal for a jump target for the platform.
   void CodeTargetAlign();