Fixes <https://bugs.gnu.org/36813>. Reported by Jakob L. Kreuze <zerodaysfordays.sdf.org@sdf.org>. * guix/gexp.scm (program-file-compiler): Pass #:system and #:target to 'gexp->script'. (load-path-expression): Add #:system and #:target and honor them. (gexp->script): Likewise. * tests/gexp.scm ("program-file #:system"): New test. * doc/guix.texi (G-Expressions): Adjust accordingly.