Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/src/regexp/interpreter-irregexp.h b/src/regexp/interpreter-irregexp.h
index 244af99..887fab6 100644
--- a/src/regexp/interpreter-irregexp.h
+++ b/src/regexp/interpreter-irregexp.h
@@ -7,12 +7,13 @@
 #ifndef V8_REGEXP_INTERPRETER_IRREGEXP_H_
 #define V8_REGEXP_INTERPRETER_IRREGEXP_H_
 
+#ifdef V8_INTERPRETED_REGEXP
+
 #include "src/regexp/jsregexp.h"
 
 namespace v8 {
 namespace internal {
 
-
 class IrregexpInterpreter {
  public:
   static RegExpImpl::IrregexpResult Match(Isolate* isolate,
@@ -26,4 +27,6 @@
 }  // namespace internal
 }  // namespace v8
 
+#endif  // V8_INTERPRETED_REGEXP
+
 #endif  // V8_REGEXP_INTERPRETER_IRREGEXP_H_