Fix performance regressions due to lazy initialization.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index fa6fce024b66b25eaa17b04ce66e10bfd4f66707..dd7253ba0651051df6fe351e18832c702fc34d8c 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -41,6 +41,7 @@
 
 #include "v8.h"
 
+#include "platform-posix.h"
 #include "platform.h"
 #include "v8threads.h"
 #include "vm-state-inl.h"
@@ -73,6 +74,12 @@ void OS::SetUp() {
 }
 
 
+void OS::PostSetUp() {
+  // Math functions depend on CPU features therefore they are initialized after
+  // CPU.
+  MathSetup();
+}
+
 uint64_t OS::CpuFeaturesImpliedByPlatform() {
   return 0;  // Nothing special about Cygwin.
 }