add preumble file to be tracked.

Author: suikan4github

src/sdk/scripts/blocks/pico_sdk_headers_preumble.hpp

@@ -0,0 +1,8 @@
+/*
+ * Pico SDK has separated directory and files for the prototype definition.
+ * To include all, we gather the include files in this one file.
+ *
+ * This file is dedicated to be read from the sdkwrapper.hpp.
+ *
+ * Not intended to be read from the application program.
+ */