Stop after the second '.' when parsing version numbers

Stop after the second '.' when parsing version numbers

Now that we are moving to x.y.z version number scheme for maintenance
releases, we ned to change ext2fs_parse_version_string and
blkid_parse_version_string to ignore the second period so we don't
have maintenance releases with a substantially bigger verison number
than the initial x.y release.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>