[fedora-virt] libguestfs - no ext3 support building on CentOS 5

[Charles Duffy <charles dyfis net>]

Howdy.

CentOS 5's stock kernel has ext3 modularized; however, while 
make-initramfs.sh allows ext2.ko and ext4.ko modules to be included in 
the generated initramfs, no such exception is made for ext3.ko (or 
jbd.ko, on which it depends), leading to the following:

====
 5/140 test_zerofree_0
mount: /dev/hda1 on /: mount: unknown filesystem type 'ext3'
test_zerofree_0 FAILED
====

Notably, ext4 is still ext4dev as of this kernel.