-v2 newrole auditing of failures due to user actions

This patch introduces two new point in the code where audit records are generated for newrole. Both points are when the attempt to newrole fails.

The first point is when the default type could not be determine for the specified role - this is audited because, as sgrubb pointed out, it is currently non-tracked path to probe the policy.

The second point is when the desired context to change to is invalid.

There record format remains unchanged. Failing to validate the desired context will result in the old and new contexts being recorded intact to the log. For the default type, the old and new contexts have not yet been obtained, so they are recorded in the log as XXX_context=?

Changes since version 1 of the patch:
* removed wrapping #ifdefs around send_audit_message()
* provided a "no-op" style function
* removed -D_GNU_SOURCE from the Makefile (as its defined in the code)
* fixed the error path of the send_audit_message function

The solution that I have for the "no-op" function is not that pretty, but the Makefile is configured with -Werror and a function which doesn't use its parameters causes warnings. Is there a better solution to this problem?

----

diff -rNau policycoreutils-1.30.29/newrole/Makefile policycoreutils-1.30.29.orig.dev/newrole/Makefile
@@ -27,7 +27,7 @@
 	LDLIBS += -laudit
 endif
 ifeq (${LOG_AUDIT_PRIV},y)
-	override CFLAGS += -DLOG_AUDIT_PRIV -D_GNU_SOURCE
+	override CFLAGS += -DLOG_AUDIT_PRIV
 	LDLIBS += -lcap
 	MODE := 4555
 else

Yes, mark the arguments with __attribute__((unused)). You'll see examples in other policycoreutils code.

Stephen Smalley
National Security Agency