Fixing ownership in airootfs customization

configs/releng/build.sh:
Fixing wrong ownership of files when copying overlay modifications from
the config's airootfs directory to the working directory in
make_customize_airootfs() by using the cp flag
'--no-preserve=ownership'.

Thanks to Marcos Mello and Francois Dupoux of sysresccd
(https://gitlab.com/fdupoux/sysresccd-src) for making this fix
available.

Closes #11

configs/releng/build.sh

@@ -95,7 +95,7 @@ make_setup_mkinitcpio() {
 
 # Customize installation (airootfs)
 make_customize_airootfs() {
-    cp -af ${script_path}/airootfs ${work_dir}/x86_64
+    cp -af --no-preserve=ownership ${script_path}/airootfs ${work_dir}/x86_64
 
     cp ${script_path}/pacman.conf ${work_dir}/x86_64/airootfs/etc