base-files: revert removal of /var/volatile/cache
base-files: revert removal of /var/volatile/cache

NILRT 8.5 safemodes do not create a /var/volatile/cache directory due to
commit 20ea59ab3e8938e8f45f5e073a315b75d4b7ec0f. This is a sane decision
for runmodes of the same version, since the opkg configuration was also
modified to not use that non-standard location for its cache.

However, some MAX workflows (AZDO 1153388) require opkg operations
performed from the safemode, via a chroot into runmode. In cases where
the runmode image predates the volatile cache change, operations will
fail with an OSError when opkg tries to create a subdirectory under the
nonexistant volatile cache.

Add the volatile cache directory back into the runtime-generated
volatile cache locations. With new runmodes, the empty directory will be
unused. On old runmodes, it will be used.

Natinst-AZDO-ID: 1159845
Signed-off-by: Alex Stewart <04cdb2793e4fb0120cc30d1c823099f3862701f4@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt