Add a soong vendor plugin for kernel config variables so we can use these in go. Change-Id: Id31f2be8fcc5aba2d965dbe815edaaf1d28279c6
*) Similar to genrule but can be used to generate content when the output directory and file structure are not known ahead of time. *) An example use case is to build kernel headers. Change-Id: I10deb7ba8825393b0b5fdbf2d96b12ad37257e12