Allow recovery to execute ashmem_device and tmpfs.

Requires execmem and ashmem_device:chr_file execute similar to bootanim
presumably for the display.

Did not see any cache_file execute denials and do not see any
exec of /cache files in the code, only reading/interpreting scripts,
so I removed cache_file rx_file_perms.

Did not see any tmpfs execute denials in /proc/last_kmsg but the
source code appears to extract the update-binary to a tmpfs mount
in /tmp and then exec it.  So I retained that rule.

Tested with adb sideload.

Change-Id: I8ca5f2cd390be1adf063f16e6280cc4cd1833c0e
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>