CLEANUP: thread: rename __decl_hathreads() to __decl_thread()

I can never figure whether it takes an "s" or not, and in the end it's
better if it matches the file's naming, so let's call it "__decl_thread".
diff --git a/include/proto/ssl_sock.h b/include/proto/ssl_sock.h
index 6966512..2cbd60b 100644
--- a/include/proto/ssl_sock.h
+++ b/include/proto/ssl_sock.h
@@ -41,7 +41,7 @@
 extern struct global_ssl global_ssl;
 extern struct ssl_bind_kw ssl_bind_kws[];
 extern struct methodVersions methodVersions[];
-__decl_hathreads(extern HA_SPINLOCK_T ckch_lock);
+__decl_thread(extern HA_SPINLOCK_T ckch_lock);
 extern struct pool_head *pool_head_ssl_capture;
 extern unsigned int openssl_engines_initialized;
 extern int nb_engines;