A64: Increase the margin for veneer checks.

src/a64/macro-assembler-a64.h

Index: src/a64/macro-assembler-a64.h
diff --git a/src/a64/macro-assembler-a64.h b/src/a64/macro-assembler-a64.h
index 7aa08eefa7386977fa2fe5c5af3530afc0704c8b..beae3609b223411ef0d2528baa9c4bdaf583ca96 100644
--- a/src/a64/macro-assembler-a64.h
+++ b/src/a64/macro-assembler-a64.h
@@ -2206,7 +2206,7 @@ class MacroAssembler : public Assembler {
  private:
   // We generate a veneer for a branch if we reach within this distance of the
   // limit of the range.
-  static const int kVeneerDistanceMargin = 2 * KB;
+  static const int kVeneerDistanceMargin = 4 * KB;
   int unresolved_branches_first_limit() const {
     ASSERT(!unresolved_branches_.empty());
     return unresolved_branches_.begin()->first;