OpenBSD nm(1) defaults to show dynamic symbol table and does not have -D
option either.
--- buildtools/wafsamba/symbols.py.orig	Tue May 14 17:30:33 2013
+++ buildtools/wafsamba/symbols.py	Tue May 14 19:58:59 2013
@@ -46,8 +46,8 @@ def symbols_extract(bld, objfiles, dynamic=False):
         return ret
 
     cmd = ["nm"]
-    if dynamic:
-        # needed for some .so files
+    if dynamic and not sys.platform.startswith("openbsd"):
+        # needed for some .so files on non-OpenBSD platforms
         cmd.append("-D")
     cmd.extend(list(objfiles))