mkdumprd: improve error message when e2fsprogs is missing
fsck.ext2/3/4 is used to check Linux ext2/3/4 file system, and they are
contained in package e2fsprogs. So if e2fsprogs is not installed, the
mkdumprd fail and report error message:
"/etc/kdump.conf: Unsupported type ext4"
With thie error message, user maybe still don't know what's wrong with
Result (if any):
Improve the error message to notice user explicitly.
Then thing will be easier for user's operation.