AOSP: mke2fs: add links for mkfs.ext[234]

AOSP: mke2fs: add links for mkfs.ext[234]

LTP tests assume existence of mkfs.ext[234] in order to create
filesystems, so we add the symbolic links.

Test: vts
Bug: 31226527
Bug: 31226662
Bug: 31226379
Bug: 31226047
Bug: 31226376
Bug: 31226714
Bug: 31226122
Bug: 31225634
Bug: 31226069
Bug: 31226031
Bug: 31225881
Bug: 31226562
Bug: 31226411
Bug: 31226410
Bug: 31226028
Bug: 31226509
Bug: 31226253
Bug: 31226404
Bug: 31226353
Bug: 31225624
Bug: 31225677
Bug: 31225191
Change-Id: I039c9e495d11dfc448f7f0de9e519394ed827d7a
From AOSP commit: cca6a5cea983546f08584e74bba271524ce37b11