fs: add sha-bang to fakeroot script

We directly running this script, so it should start with a sha-bang (not
sure why/how it works today...).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

fs/common.mk

@@ -76,6 +76,7 @@ $$(BINARIES_DIR)/rootfs.$(1): target-finalize $$(ROOTFS_$(2)_DEPENDENCIES)
 	rm -f $$(FAKEROOT_SCRIPT)
 	rm -f $$(TARGET_DIR_WARNING_FILE)
 	rm -f $$(USERS_TABLE)
+	echo '#!/bin/sh' > $$(FAKEROOT_SCRIPT)
 	echo "set -e" >> $$(FAKEROOT_SCRIPT)
 	echo "chown -h -R 0:0 $$(TARGET_DIR)" >> $$(FAKEROOT_SCRIPT)
 ifneq ($$(ROOTFS_USERS_TABLES),)