Fix GOROOT for fish shells

Follow-up of #22

Author: syndbg

libexec/goenv-init

@@ -87,13 +87,13 @@ mkdir -p "${GOENV_ROOT}/"{shims,versions}
 case "$shell" in
 fish )
   echo "setenv PATH '${GOENV_ROOT}/shims' \$PATH"
-  echo "setenv GOROOT '$(goenv prefix)'"
   echo "setenv GOENV_SHELL $shell"
+  echo "setenv GOROOT (goenv prefix)"
 ;;
 * )
   echo 'export PATH="'${GOENV_ROOT}'/shims:${PATH}"'
-  echo 'export GOROOT="$(goenv prefix)"'
   echo "export GOENV_SHELL=$shell"
+  echo 'export GOROOT="$(goenv prefix)"'
 ;;
 esac