guix: Adjust environment setup so extensions are located without propagating Guix.

This change makes GUIX_EXTENSIONS_PATH handled specially so package extensions
do not need to propagate Guix or extend their native search path to locate the
extension.

* gnu/home/services.scm (environment-variables->setup-environment-script):
Setup GUIX_EXTENSIONS_PATH to locate extensions in profiles that do not
contain Guix.
* gnu/system.scm (operating-system-etc-service): Likewise.
* gnu/packages/containers.scm (guix-compose): Remove unneeded
'native-search-paths' specification.
* gnu/packages/package-management.scm (toys): Likewise.
(guix-xsearch): Likewise.
* guix/search-paths.scm ($GUIX_EXTENSIONS_PATH): Adjust comment.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/gnu/home/services.scm b/gnu/home/services.scm
index 93d6881954c..f7d0ff08228 100644
--- a/gnu/home/services.scm
+++ b/gnu/home/services.scm
@@ -330,6 +330,10 @@ case $XCURSOR_PATH in
   *$GUIX_PROFILE/share/icons*) ;;
   *) export XCURSOR_PATH=$GUIX_PROFILE/share/icons:$XCURSOR_PATH ;;
 esac
+case $GUIX_EXTENSIONS_PATH in
+  *$GUIX_PROFILE/share/guix/extensions*) ;;
+  *) export GUIX_EXTENSIONS_PATH=$GUIX_PROFILE/share/guix/extensions:$GUIX_EXTENSIONS_PATH ;;
+esac
 
 # Keep the shell environment clean.
 unset GUIX_PROFILE PROFILE_FILE