Added Unix Implementations for Socket Opt Functions

Added internal functions and implementations for sockopt functions

- Added 4 internal functions: one to retrieve OMR to OS mapping
  for socket levels, one to retrieve OMR to OS mapping for socket
  options, two to wrap the code for the socket option functions
  to reduce clutter.
- Added simple implemnentations for the 6 socket options functions.

Issue: eclipse-omr#5158

Signed-off-by: Haley Cao <haleycao88@hotmail.com>

port/unix/omrsock.c

@@ -807,7 +807,6 @@ get_opt(struct OMRPortLibrary *portLibrary, omr_os_socket sock, int32_t optlevel
 
 	return 0;
 }
-
 int32_t
 omrsock_setsockopt_int(struct OMRPortLibrary *portLibrary, omrsock_socket_t handle, int32_t optlevel, int32_t optname, int32_t *optval)
 {