Added check for non existant directory in order to speed up boot a little

config/grub/config/grub.cfg

@@ -42,15 +42,17 @@ fi
 
 function try_user_config {
 	set root="${1}"
-
 	# The @/... entries are for cases where the BTRFS filesystem is being used
 	for dir in boot grub grub2 boot/grub boot/grub2 @/boot @/grub @/grub2 @/boot/grub @/boot/grub2; do
+                # In order to save time, we do not attempt anything on non existing directory.
+                if [ -d /"${dir}"/ ]; then
 			for name in '' osboot_ autoboot_ libreboot_ coreboot_; do
 				if [ -f /"${dir}"/"${name}"grub.cfg ]; then
 					unset superusers
 					configfile /"${dir}"/"${name}"grub.cfg
 				fi
 			done
+		fi
 	done
 }
 function search_grub {