When applying a file based OTA, the recovery scripts sometimes
transiently label a directory as an exec_type. This occurs on
hammerhead when the OTA generation scripts generate lines of the
form:

  set_metadata_recursive("/system/vendor/bin", "uid", 0, "gid", 2000, "dmode", 0755, "fmode", 0755, "capabilities", 0x0, "selabel", "u:object_r:vss_exec:s0");
  set_metadata("/system/vendor/bin", "uid", 0, "gid", 2000, "mode", 0755, "capabilities", 0x0, "selabel", "u:object_r:system_file:s0");

which has the effect of transiently labeling the /system/vendor/bin
directory as vss_exec.

Allow this behavior for now, even though it's obviously a bug.

Also, allow recovery to read through the /dev directory.

Addresses the following denials:
  avc:  denied  { read } for  pid=143 comm="recovery" name="/" dev="tmpfs" ino=8252 scontext=u:r:recovery:s0 tcontext=u:object_r:device:s0 tclass=dir
  avc:  denied  { open } for  pid=143 comm="recovery" name="/" dev="tmpfs" ino=8252 scontext=u:r:recovery:s0 tcontext=u:object_r:device:s0 tclass=dir
  avc:  denied  { relabelto } for  pid=142 comm="update_binary" name="bin" dev="mmcblk0p25" ino=1438 scontext=u:r:recovery:s0 tcontext=u:object_r:vss_exec:s0 tclass=dir
  avc:  denied  { getattr } for  pid=142 comm="update_binary" path="/system/vendor/bin" dev="mmcblk0p25" ino=1438 scontext=u:r:recovery:s0 tcontext=u:object_r:vss_exec:s0 tclass=dir
  avc:  denied  { setattr } for  pid=142 comm="update_binary" name="bin" dev="mmcblk0p25" ino=1438 scontext=u:r:recovery:s0 tcontext=u:object_r:vss_exec:s0 tclass=dir
  avc:  denied  { relabelfrom } for  pid=142 comm="update_binary" name="bin" dev="mmcblk0p25" ino=1438 scontext=u:r:recovery:s0 tcontext=u:object_r:vss_exec:s0 tclass=dir

Bug: 15575013
Change-Id: I743bea356382d3c23c136465dc5b434878370127