Fix dartbug.com/10415:

runtime/vm/version_in.cc

Index: runtime/vm/version_in.cc
===================================================================
--- runtime/vm/version_in.cc	(revision 22412)
+++ runtime/vm/version_in.cc	(working copy)
@@ -4,8 +4,28 @@
 
 #include "vm/version.h"
 
+#include "vm/cpu.h"
+#include "vm/os.h"
+
 namespace dart {
 
+// TODO(iposva): Avoid racy initialization.
+static const char* formatted_version = NULL;
+
+const char* Version::String() {
+  if (formatted_version == NULL) {
+    const char* format = "%s on \"%s_%s\"";
+    const char* os = OS::Name();
+    const char* arch = CPU::Id();
+
+    intptr_t len = OS::SNPrint(NULL, 0, format, str_, os, arch);
+    char* buffer = reinterpret_cast<char*>(malloc(len + 1));
+    OS::SNPrint(buffer, (len + 1), format, str_, os, arch);
+    formatted_version = buffer;
+  }
+  return formatted_version;
+}
+
 const char* Version::str_ = "{{VERSION_STR}} ({{BUILD_TIME}})";
 
 }  // namespace dart