oeqa/pam: Need shadow installed for the tests

Distros may not use shadow for login manager
secondly login --help returns 1 only with shadow provided login
utility, with busybox it returns normal 0, the testcase clearly
assumes shadow being part of image, therefore add needed
checks to ensure the pre-requisites are met

(From OE-Core rev: 0820aeba74869bf6e85b200f39bc610a43ab9a7a)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/runtime/cases/pam.py

@@ -8,11 +8,14 @@
 from oeqa.runtime.case import OERuntimeTestCase
 from oeqa.core.decorator.depends import OETestDepends
 from oeqa.core.decorator.data import skipIfNotFeature
+from oeqa.runtime.decorator.package import OEHasPackage
 
 class PamBasicTest(OERuntimeTestCase):
 
     @skipIfNotFeature('pam', 'Test requires pam to be in DISTRO_FEATURES')
     @OETestDepends(['ssh.SSHTest.test_ssh'])
+    @OEHasPackage(['shadow'])
+    @OEHasPackage(['shadow-base'])
     def test_pam(self):
         status, output = self.target.run('login --help')
         msg = ('login command does not work as expected. '