Support non-genisoimage binaries

Updates tinyipa build script so it can use one of the multiple
different ISO filesystem generation tools in the ecosystem.

Also updates the dib docs which states IPA requires genisoimage,
which is... not... true.

Change-Id: I505aed2ec98674a0495174219609694042d59070

doc/source/admin/dib.rst

@@ -240,7 +240,7 @@ Beyond installing the ironic-python-agent, this element does the following:
 * Disables the ``iptables`` service on SysV and systemd based systems.
 * Disables the ``ufw`` service on Upstart based systems.
 * Installs packages required for the operation of the ironic-python-agent::
-  ``qemu-utils`` ``parted`` ``hdparm`` ``util-linux`` ``genisoimage``
+  ``qemu-utils`` ``parted`` ``hdparm`` ``util-linux``
 * When installing from source, ``python-dev`` and ``gcc`` are also installed
   in order to support source based installation of ironic-python-agent and its
   dependencies.

doc/source/admin/tinyipa.rst

@@ -27,7 +27,7 @@ Then you need to install some utilities. For the main build script:
 
 For building an ISO you'll also need:
 
-* genisoimage
+* mkisofs, genisoimage, or xorrisofs
 
 Building
 --------

tinyipa/build-iso.sh

@@ -17,4 +17,19 @@ cp build_files/syslinux-${SYSLINUX_VERSION}/bios/core/isolinux.bin newiso/boot/i
 cp build_files/isolinux.cfg newiso/boot/isolinux/.
 cp tinyipa${BRANCH_EXT}.gz newiso/boot/corepure64.gz
 cp tinyipa${BRANCH_EXT}.vmlinuz newiso/boot/vmlinuz64
-genisoimage -l -r -J -R -V TC-custom -no-emul-boot -boot-load-size 4 -boot-info-table -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat -o tinyipa.iso newiso
+
+set +e
+ISO_BUILDER=""
+
+for builder in mkisofs genisoimage xorrisofs; do
+    if $($builder --help); then
+        ISO_BUILDER=$builder
+    fi
+done
+if [ -z "$ISO_BUILDER" ]; then
+   echo "Please install a ISO filesystem builder utility such as mkisofs, genisoimage, or xorrisofs."
+   exit 1
+fi
+
+set -e
+$ISO_BUILDER -l -r -J -R -V TC-custom -no-emul-boot -boot-load-size 4 -boot-info-table -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat -o tinyipa.iso newiso