socket: Introduce function to obtain socket name

Using this function, one can obtain a human-readable string identifying
the host and port names of the socket.

Change-Id: Ib5de5c7b9effe1b0a363e4473a7be7fa38ca6ef3
diff --git a/include/osmocom/core/socket.h b/include/osmocom/core/socket.h
index 6ef0912..4f00e30 100644
--- a/include/osmocom/core/socket.h
+++ b/include/osmocom/core/socket.h
@@ -38,4 +38,6 @@
 int osmo_sock_unix_init_ofd(struct osmo_fd *ofd, uint16_t type, uint8_t proto,
 			    const char *socket_path, unsigned int flags);
 
+char *osmo_sock_get_name(void *ctx, int fd);
+
 /*! @} */