Revert "Revert "Upgrade to 5.0.71.48""

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

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
diff --git a/test/mjsunit/regexp-compile.js b/test/mjsunit/regexp-compile.js
index 6a24325..92c3f7b 100644
--- a/test/mjsunit/regexp-compile.js
+++ b/test/mjsunit/regexp-compile.js
@@ -40,3 +40,5 @@
 re.compile("(y)");
 
 assertEquals(["y", "y"], re.exec("axyb"));
+
+assertEquals(2, re.compile.length);