BUILD/MINOR: deviceatlas: enable thread support

DeviceAtlas detection being multi-thread safe, we enable the
new thread feature support.
Needs to be backported to 1.8 branch.
diff --git a/src/da.c b/src/da.c
index 0669cba..685a79d 100644
--- a/src/da.c
+++ b/src/da.c
@@ -121,12 +121,6 @@
 		size_t atlasimglen;
 		da_status_t status;
 
-		if (global.nbthread > 1) {
-			ha_alert("deviceatlas: multithreading is not supported for now.\n");
-			err_code |= ERR_ALERT | ERR_FATAL;
-			goto out;
-		}
-
 		jsonp = fopen(global_deviceatlas.jsonpath, "r");
 		if (jsonp == 0) {
 			ha_alert("deviceatlas : '%s' json file has invalid path or is not readable.\n",