fish: Fix recursive fish_user_path setting

Changing the scope flag from "export" to "global" seems to fix the
issue. See also
fish-shell/fish-shell#527 (comment)
for reference

config/fish/config.fish

@@ -1,8 +1,8 @@
 # Set binary paths dependent on local environment
 [ -e "/usr/local/opt/node@10/bin" ]; and set -g fish_user_paths "/usr/local/opt/node@10/bin" $fish_user_paths
-[ -e "$HOME/.composer/vendor/bin" ]; and set -x fish_user_paths $HOME/.composer/vendor/bin $fish_user_paths
+[ -e "$HOME/.composer/vendor/bin" ]; and set -g fish_user_paths $HOME/.composer/vendor/bin $fish_user_paths
 # Keep this at the bottom to make sure $HOME/bin is the first entry
-[ -e "$HOME/bin" ]; and set -x fish_user_paths $HOME/bin $fish_user_paths
+[ -e "$HOME/bin" ]; and set -g fish_user_paths $HOME/bin $fish_user_paths
 
 source ~/.config/fish/abbrevs.fish