+## Add some environment variables, if they were passed via the environment
+## rather than on the command-line.
+for var in CFLAGS CPPFLAGS LDFLAGS; do
+ case "$emacs_config_options" in
+ *$var=*) continue ;;
+ esac
+ eval val="\$${var}"
+ test x"$val" = x && continue
+ emacs_config_options="${emacs_config_options}${emacs_config_options:+ }$var=\"$val\""
+done
+