Fix performance regressions due to lazy initialization.

src/platform-freebsd.cc

Index: src/platform-freebsd.cc
diff --git a/src/platform-freebsd.cc b/src/platform-freebsd.cc
index 2a9e174e35bc6bcb1c1ffc3ab29975c7844f4263..6a004ea7fa0fec3ddef51c680538ce01fa8614a6 100644
--- a/src/platform-freebsd.cc
+++ b/src/platform-freebsd.cc
@@ -54,6 +54,7 @@
 #include "v8.h"
 #include "v8threads.h"
 
+#include "platform-posix.h"
 #include "platform.h"
 #include "vm-state-inl.h"
 
@@ -91,6 +92,13 @@ void OS::SetUp() {
 }
 
 
+void OS::PostSetUp() {
+  // Math functions depend on CPU features therefore they are initialized after
+  // CPU.
+  MathSetup();
+}
+
+
 void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) {
   __asm__ __volatile__("" : : : "memory");
   *ptr = value;