Subzero: Use a "deterministic" random shuffle for register allocation.

To make this work, Subzero provides its own RandomShuffle() as a replacement for std::random_shuffle(), and the Subzero implementation doesn't depend on the stdlib implementation.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4129
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/1072913002

unittest/IceELFSectionTest.cpp

diff --git a/unittest/IceELFSectionTest.cpp b/unittest/IceELFSectionTest.cpp
index 8dbcc65..57e43c1 100644
--- a/unittest/IceELFSectionTest.cpp
+++ b/unittest/IceELFSectionTest.cpp
@@ -90,8 +90,11 @@
   Strings.push_back(".shstrtab");
   Strings.push_back("_start");
   const SizeT NumTests = 128;
+  const uint64_t RandomSeed = 12345; // arbitrary value for now
+  RandomNumberGenerator R(RandomSeed);
+  RandomNumberGeneratorWrapper RNG(R);
   for (SizeT i = 0; i < NumTests; ++i) {
-    std::random_shuffle(Strings.begin(), Strings.end());
+    RandomShuffle(Strings.begin(), Strings.end(), RNG);
     ELFStringTableSection Strtab(".strtab", SHT_STRTAB, 0, 1, 0);
     for (auto &S : Strings) {
       Strtab.add(S);