libcgroup Test: libcgroup-create-function-for-attach_task-api

libcgroup Test: libcgroup-create-function-for-attach_task-api

This patch creates a function test_cgroup_attach_task() to test the libcgroup
api cgroup_attach_task() under different scenario. In the earlier approach we
were not usong functions and were testing the api sequentialy under different
conditions. The new approach has a single function for 1 api which can handle
the testing under all conditions. The advantage is that the test case becomes
thread safe as all the variables are now declared on stack. The other benefit
is that the code repetition has reduced now.

Signed-off-by:	 Sudhir Kumar	 <skumar@linux.vnet.ibm.com>

git-svn-id: https://libcg.svn.sourceforge.net/svnroot/libcg/trunk@268 4f4bb910-9a46-0410-90c8-c897d4f1cd53