Fix bt_extract_eir_name to use GLib memory allocation

The string returned by bt_extract_eir_name is freed using g_free so
GLib's own allocators should be used instead of libc ones.
diff --git a/src/glib-helper.c b/src/glib-helper.c
index f32aac3..8181f4d 100644
--- a/src/glib-helper.c
+++ b/src/glib-helper.c
@@ -753,8 +753,8 @@
 	case EIR_NAME_SHORT:
 	case EIR_NAME_COMPLETE:
 		if (!g_utf8_validate((char *) (data + 2), data[0] - 1, NULL))
-			return strdup("");
-		return strndup((char *) (data + 2), data[0] - 1);
+			return g_strdup("");
+		return g_strndup((char *) (data + 2), data[0] - 1);
 	}
 
 	return NULL;