Cherry-pick upstream bug fixes from Git.

This is pending an 1.44.2 release, and contains these fixes from maint:
filefrag: avoid temporary buffer overflow
libext2fs: add sanity checks for ea_in_inode
e2image: fix metadata image handling on big endian systems
e2fsck: warn if checkinterval and broken_system_clock both set
tests: don't leave temp files behind after running i_bitmaps
tests: add new test f_ea_inode_self_ref
chattr.1: 'a' and 'i' attribute do not affect existing file

MFH: 2018Q2