LU-14356 utils: change position of the -lext2fs option

LU-14356 utils: change position of the -lext2fs option

This patch changes the position of the -lext2fs option
in the gcc command line so as to resolve the following
issue:

mount_osd_ldiskfs.so: undefined symbol: unix_io_manager

Change-Id: I9ceaca867697c132b8d4a7800169101a024d17b8
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/41305
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>