libc: Import strlcat from FreeBSD project

From commit: 21571b1d140ae7bb44e94c0afba2ec61456b275b
Made small changes to fit into TF-A project

Change-Id: I07fd7fe1037857f6b299c35367c104fb51fa5cfa
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
2 files changed