gnu: Use INSTALL-FILE where appropriate.

gnu: Use INSTALL-FILE where appropriate.

* gnu/packages/admin.scm (wpa-supplicant-minimal): Substitute the simpler
INSTALL-FILE for COPY-FILE when invoked with redundant arguments.
* gnu/packages/bioinformatics.scm (couger, aragorn, express-beta-diversity,
edirect, fasttree, rsem, samtools-0.1): Likewise.
* gnu/packages/code.scm (withershins): Likewise.
* gnu/packages/conky.scm (conky): Likewise.
* gnu/packages/debug.scm (delta, american-fuzzy-lop): Likewise.
* gnu/packages/emacs.scm (emacs-mit-scheme-doc): Likewise.
* gnu/packages/engineering.scm (librecad): Likewise.