openbsd minimal build options

librocksdb-sys/build.rs

@@ -162,6 +162,10 @@ fn build_rocksdb() {
         config.define("OS_FREEBSD", None);
         config.define("ROCKSDB_PLATFORM_POSIX", None);
         config.define("ROCKSDB_LIB_IO_POSIX", None);
+    } else if target.contains("openbsd") {
+        config.define("OS_OPENBSD", None);
+        config.define("ROCKSDB_PLATFORM_POSIX", None);
+        config.define("ROCKSDB_LIB_IO_POSIX", None);
     } else if target.contains("windows") {
         link("rpcrt4", false);
         link("shlwapi", false);