testing: Use little-endian packing in gpt tests

Fix gpt-header-move.py and gpt-header-munge to use little endian when
packing and unpacking. This allows us to turn the t0210 and t0211 tests
back on for big-endian systems.

* tests/gpt-header-move.py: Use little endian for pack/unpack
* tests/gpt-header-munge: Same
* tests/t-lib-helpers.sh: Add requires_64bit_ that checks for x86_64 and ppc64
* tests/t0210-gpt-resized-partition-entry-array.sh: Remove x86_64 test
* tests/t0211-gpt-rewrite-header.sh: Same
libparted: fix several integer overflows with dvh labels

Integer overflows was found in libparted/labels/dvh.c, while attemptting
assign unsigned int values to int types in some places.

Defined by unsigned int instead.

* libparted/labels/dvh.h: Change int to unsigned int

Signed-off-by: Ming Liu <ming.liu@windriver.com>
Signed-off-by: Brian C. Lane <bcl@redhat.com>
tests: Use force for xfs in t1700 and a larger file

Also use sparse files that are (with 512B blocks) 128M so that they are
large enough for all the filesystems.

* tests/t1700-probe-fs.sh: Make changes.
tests: t1700 change count to seek

Fix a typo when changing to sparse images.

* tests/t1700-probe-fs.sh: count should be seek.