Increase policy version to 26.

Increase the SELinux policy version to 26.  This is needed
for name-based transitions used by the manta sepolicy.
Requires kernel 3.0 or higher.

Change-Id: I046fa9f7122f77506c70b2c735345bc0194935df
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>