Fix allocator bump in printf string allocation

Fixes #373.

Author: gchatelet

src/utils/list_cpu_features.c

@@ -148,11 +148,13 @@ static Node* CreatePrintfString(const char* format, ...) {
   const int written = vsnprintf(ptr, gBumpAllocator.size, format, arglist);
   va_end(arglist);
   if (written < 0 || written >= (int)gBumpAllocator.size) internal_error();
-  return CreateConstantString((char*)BA_Bump(written));
+  const int null_terminated_written = written + 1;
+  return CreateConstantString((char*)BA_Bump(null_terminated_written));
 }
 
-// Adds a string node.
+// Adds a non empty string node.
 static Node* CreateString(const char* value) {
+  if (value == NULL || *value == '\0') internal_error();
   return CreatePrintfString("%s", value);
 }