CLEANUP: build: rename some build macros to use the USE_* ones

We still have quite a number of build macros which are mapped 1:1 to a
USE_something setting in the makefile but which have a different name.
This patch cleans this up by renaming them to use the USE_something
one, allowing to clean up the makefile and make it more obvious when
reading the code what build option needs to be added.

The following renames were done :

 ENABLE_POLL -> USE_POLL
 ENABLE_EPOLL -> USE_EPOLL
 ENABLE_KQUEUE -> USE_KQUEUE
 ENABLE_EVPORTS -> USE_EVPORTS
 TPROXY -> USE_TPROXY
 NETFILTER -> USE_NETFILTER
 NEED_CRYPT_H -> USE_CRYPT_H
 CONFIG_HAP_CRYPT -> USE_LIBCRYPT
 CONFIG_HAP_NS -> DUSE_NS
 CONFIG_HAP_LINUX_SPLICE -> USE_LINUX_SPLICE
 CONFIG_HAP_LINUX_TPROXY -> USE_LINUX_TPROXY
 CONFIG_HAP_LINUX_VSYSCALL -> USE_LINUX_VSYSCALL
diff --git a/src/cli.c b/src/cli.c
index 23ab57b..4b430a9 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -1654,7 +1654,7 @@
 				memcpy(&tmpfd[i % MAX_SEND_FD], &l->fd, sizeof(l->fd));
 				if (!l->netns)
 					tmpbuf[curoff++] = 0;
-#ifdef CONFIG_HAP_NS
+#ifdef USE_NS
 				else {
 					char *name = l->netns->node.key;
 					unsigned char len = l->netns->name_len;