This is a followup to d6b5aa0b031f0e7091f7424ac616d1c4d10fed5b.
* guix/self.scm (%config-variables): Remove %CONFIG-DIRECTORY,
%STATE-DIRECTORY, %STORE-DATABASE-DIRECTORY, and %STORE-DIRECTORY.
(make-config.scm): Define them here.
* build-aux/build-self.scm (%config-variables, make-config.scm):
Likewise.