sysutils/e2fsprogs: bugfix update to 1.46.6

ChangeLog: https://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.46.6

Add patch to make m_offset reliable. Due to some race conditions on the
pipeline between FreeBSD's yes a, which emits 8190-long writes on
13-STABLE, and GNU dd (gdd), which it pipes its output into, gdd can
sometimes receive short reads occasionally, and because the count=
normally is the number of read(2) calls dispatched, this then leads to a
shorter reference "file system" that we crcsum, and that causes false
negative test results. gdd warns that iflag=fullblock would avoid
effects of short reads, but this warning is discarded in the test
script. Anyways, patch m_offset to use dd's and gdd's iflag=fullblock,
which causes (g)dd to call read(2) again until the block is full for
each nominal block, so we definitely read the desired output size 512 kB
no matter what shorter blocks might travel through the pipeline.

MFH: 2023Q1