feat(lib): implement memcpy_s in lib

To support memcpy_s for better security purpose
to avoid overflowing the dest while copy from src.

Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
Change-Id: I63c3ea6a3e99c10d69be6bce04843c14b0a28a4d
diff --git a/lib/libc/libc.mk b/lib/libc/libc.mk
index b75d09c..5eb8b52 100644
--- a/lib/libc/libc.mk
+++ b/lib/libc/libc.mk
@@ -11,6 +11,7 @@
 			memchr.c			\
 			memcmp.c			\
 			memcpy.c			\
+			memcpy_s.c			\
 			memmove.c			\
 			memrchr.c			\
 			memset.c			\