Never mind. Problem was with /usr/lib/ocaml/dynlink/META which was
missing native library spec.
(My actual project that didn't compile used native mode)

Fix:

--- /usr/lib/ocaml/dynlink/META.orig    2009-02-26 05:23:21.000000000 -0500
+++ /usr/lib/ocaml/dynlink/META 2009-10-14 15:02:56.253171783 -0400
@@ -5,4 +5,4 @@
 directory = "^"
 browse_interfaces = " Btype Bytesections Clflags Config Consistbl Dll
Dynlink Ident Meta Misc Opcodes Path Predef Runtimedef Symtable Tbl
Types "
 archive(byte) = "dynlink.cma"
-
+archive(native) = "dynlink.cmxa"