TEST: Place exclusions for RHEL-5

Place exclusions for a couple of tests that fail under RHEL-5.

	https://bugzilla.redhat.com/show_bug.cgi?id=1075655

The problems are:

 (1) keyctl/show/valid fails because "keyctl show" doesn't handle nested
     keyrings with a depth of more than 2-3 correctly.

 (2) keyctl/show/valid fails because the output of "keyctl show" doesn't allow
     a big enough field for the key serial ID.

 (3) keyctl/padd/useradd fails because the "keyctl padd" & co. are limited to
     ~64KB of data rather than 1MB-1.

 (4) keyctl/padd/useradd fails because the "keyctl padd" & co. can't handle NUL
     chars in their input.

Signed-off-by: David Howells <dhowells@redhat.com>
TEST: Disable AVC checking in the bz1031154 testcase

Disable checks for AVCs by the test infrastructure in the bz1031154 testcase
because we intentionally generate AVCs as part of the test.

Signed-off-by: David Howells <dhowells@redhat.com>
TEST: 'keyctl invalidate' exists from keyutils-1.5.6, not keyutils-3.5-rc1

Fix mixed up version number checking.  3.5-rc1 is a kernel version number, not
a keyutils one.

Signed-off-by: David Howells <dhowells@redhat.com>