mkarchiso: do not set default mksquashfs options

Remove hardcoded '-comp xz', it prevents using mksquashfs defaults.

Fixes #112.

README.profile.rst

@@ -51,8 +51,7 @@ The image file is constructed from some of the variables in **profiledef.sh**: `
   - `ext4+squashfs`: Create an ext4 partition, copy the airootfs work directory to it and create a squashfs image from it
   - `erofs`: Create an EROFS image for the airootfs work directory
 * `airootfs_image_tool_options`: An array of options to pass to the tool to create the airootfs image. `mksquashfs` and
-  `mkfs.erofs` are supported. See `mksquashfs --help` or `mkfs.erofs --help` for all possible options (defaults to
-  `('-comp' 'xz')` for squashfs).
+  `mkfs.erofs` are supported. See `mksquashfs --help` or `mkfs.erofs --help` for all possible options.
 * `file_permissions`: An associative array that lists files and/or directories who need specific ownership or
   permissions. The array's keys contain the path and the value is a colon separated list of owner UID, owner GID and
   access mode. E.g. `file_permissions=(["/etc/shadow"]="0:0:400")`. When directories are listed with a trailing backslash ("/") **all** files and directories contained within the listed directory will have the same owner UID, owner GID, and access mode applied recursively.

archiso/mkarchiso

@@ -155,11 +155,6 @@ _cleanup_airootfs() {
 }
 
 _run_mksquashfs() {
-    # Set default mksquashfs options
-    if (( ${#airootfs_image_tool_options[@]} < 1 )); then
-        airootfs_image_tool_options=('-comp' 'xz')
-    fi
-
     local image_path="${isofs_dir}/${install_dir}/${arch}/airootfs.sfs"
     if [[ "${quiet}" == "y" ]]; then
         mksquashfs "$@" "${image_path}" -noappend "${airootfs_image_tool_options[@]}" -no-progress > /dev/null