First draft of the sh4 port

src/platform-posix.cc

Index: src/platform-posix.cc
diff --git a/src/platform-posix.cc b/src/platform-posix.cc
index 3bc83733ca21249808c74388dd98de6be4125497..1c65be226c385ffbe47305caf84e27c57e5a102a 100644
--- a/src/platform-posix.cc
+++ b/src/platform-posix.cc
@@ -149,7 +149,19 @@ UNARY_MATH_FUNCTION(sqrt, CreateSqrtFunction())
 
 double OS::nan_value() {
   // NAN from math.h is defined in C99 and not in POSIX.
+
+#if defined(V8_TARGET_ARCH_SH4)
+  // Return a qNaN as expected by the v8 core. In sh4 tool chain, the NAN macro
+  // is defined to be an sNaN while the C specifications require a qNaN.
+  union {
+    uint64_t ui64;
+    double d;
+  } value;
+  value.ui64 = (static_cast<uint64_t>(0x7ff00000) << 32) | 0x00000001;
+  return value.d;
+#else
   return NAN;
+#endif
 }