BUILD: ssl: fix two remaining occurrences of #if USE_OPENSSL

One was in backend.c and the other one in hlua.c. No other candidate
was found with "git grep '^#if\s*USE'". It's worth noting that 3
other such tests exist for SSL_OP_NO_{SSLv3,TLSv1_1,TLSv1_2} but
that these ones are properly set to 0 in openssl-compat.h when not
defined.
diff --git a/src/backend.c b/src/backend.c
index adbd606..7143ba6 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1662,7 +1662,7 @@
 		}
 	}
 
-#if USE_OPENSSL && (defined(OPENSSL_IS_BORINGSSL) || (HA_OPENSSL_VERSION_NUMBER >= 0x10101000L))
+#if defined(USE_OPENSSL) && (defined(OPENSSL_IS_BORINGSSL) || (HA_OPENSSL_VERSION_NUMBER >= 0x10101000L))
 
 	if (!reuse && cli_conn && srv && srv_conn->mux &&
 	    (srv->ssl_ctx.options & SRV_SSL_O_EARLY_DATA) &&