tirpc: Fix compiler error on rhel 5.5
tirpc: Fix compiler error on rhel 5.5

When compiled on rhel 5.5, the build fails due to a missing
SOCK_CLOEXEC flag that is not available in the downstream kernel.
This patch corrects this error by checking to see if the flag is
present before using it

Signed-off-by: Allison Henderson <f908fb55b00b5234257aee48327eaf34b75167a0@linux.vnet.ibm.com>
Signed-off-by: Steve Dickson <305cc9d5027c0f4e08c2697d4cabde07a8221669@redhat.com>

Distrotech/libtirpc,Distrotech/libtirpc,Distrotech/libtirpc