which version of mtd-utils is used by your build? I’ve run into problems when the build uses newer versions of the tools. Also, any printf’s that are prepended by if (verbose) can be commented out safely.
Also, if you only want to compile your own module(s), you technically don’t need to compile any tools that are used for the OS itself. So you could just remove mtd-utils from the build.
Sorry I cannot be more of a help at this time.