REORG: include: move ssl_sock.h to haproxy/ssl_sock{,-t}.h

Almost nothing changed, just moved a static inline at the end and moved
an export from the types to the main file.
diff --git a/src/backend.c b/src/backend.c
index 8387694..b730df7 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -35,6 +35,7 @@
 #include <haproxy/obj_type.h>
 #include <haproxy/payload.h>
 #include <haproxy/session.h>
+#include <haproxy/ssl_sock.h>
 #include <haproxy/task.h>
 #include <haproxy/ticks.h>
 #include <haproxy/time.h>
@@ -55,7 +56,6 @@
 #include <proto/server.h>
 #include <proto/stream.h>
 #include <proto/stream_interface.h>
-#include <proto/ssl_sock.h>
 
 #define TRACE_SOURCE &trace_strm