buildhistory.bbclass: do not influence sstate of do_rootfs
Enabling or disabling buildhistory caused a rebuild of images, which
is undesirable. For example, it prevented image reuse from a main
build with buildhistory in a following oe-selftest where buildhistory
must be disabled.
The reason are the additional ROOTFS_POSTUNINSTALL_COMMAND and
ROOTFS_POSTUNINSTALL_COMMAND entries. Those need to be excluded both
via vardepvalueexclude and vardepsexclude.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
