tools/e2fsprogs: fix build with system libblkid probe API

tools/e2fsprogs: fix build with system libblkid probe API

When building on a host with e2fsprogs >= 1.47.0 installed, configure
detects the system libblkid probe API (blkid_probe_get_partitions etc.)
and sets ac_cv_lib_blkid_blkid_get_cache=yes. This causes plausible.c
to be compiled with HAVE_BLKID_PROBE_GET_PARTITIONS defined, but the
host build links against the internal blkid stub, resulting in:

  plausible.c: error: unknown type name 'blkid_probe'

Override the configure cache variables to prevent detection of the
system libblkid probe API, ensuring the internal stub is used
consistently.

Signed-off-by: seuros <openwrt@seuros.com>
Link: https://github.com/openwrt/openwrt/pull/22368
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>