Add libminshacrypt static lib

This is a sha-only version of libmincrypt, to provide the new
SHA_hash implementation to binaries that require libcrypto_static
Add support for ECDSA P-256 with SHA256

This adds a small EC library that is capable of verifying a signature of
SHA256 with ECDSA on the NIST P-256 curve.

Change-Id: I2a16639c92a77e8e4783c47ffbc56676de56eb59
restorecon_recursive("/sys") speed boot time

Currently, the restorecon_recursive("/sys") call in
init.c takes approx 2 seconds on hammerhead. This change
reduces the delay to 1.2 seconds.

1) Avoid double stat call when using nftw (time savings
of 0.3 seconds)
2) Avoid the repeated calls to is_selinux_enabled() (time
savings of 0.5 seconds)

Avoid calling lsetfilecon if the file is already properly
labeled. This doesn't speed up the restorecon on /sys,
but it should help when handling files on /data.

Change-Id: Icf344edc5bfc9520d3a0ebd9527a065d29832f87
Move restorecon and restorecon_recursive code to libselinux.

This requires telling libselinux to use the sehandle already
obtained by init rather than re-acquiring it internally.  init
retains ownership of the sehandle because it performs the
initial load, uses the sehandle for other purposes (e.g. labeling
of directories created via mkdir and labeling of socket files),
and handles the policy reload property trigger.

Change-Id: I4a380caab7f8481c33eb64fcdb16b6cabe918ebd
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Convert all selinux_android_restorecon and _setfilecon calls to new API.

libselinux selinux_android_restorecon API is changing to the more
general interface with flags and dropping the older variants.

Also get rid of the old, no longer used selinux_android_setfilecon API
and rename selinux_android_setfilecon2 to it as it is the only API in use.

Change-Id: I1e71ec398ccdc24cac4ec76f1b858d0f680f4925

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Brandon McAnsh <brandonm@matricom.net>