only prepend underscore to symbol names when doing dlsym() on a.out

OpenBSD architectures - fixes ELF plugin loading; ok jakob

security/cyrus-sasl2/patches/patch-lib_dlopen_c

@@ -0,0 +1,21 @@
+$OpenBSD: patch-lib_dlopen_c,v 1.1 2002/07/20 18:33:21 pvalchev Exp $
+--- lib/dlopen.c.orig	Sun Jul  7 15:13:39 2002
++++ lib/dlopen.c	Sun Jul  7 15:14:43 2002
+@@ -157,7 +157,7 @@ int _sasl_locate_entry(void *library, co
+ {
+ /* note that we still check for known problem systems in
+  * case we are cross-compiling */
+-#if defined(DLSYM_NEEDS_UNDERSCORE) || defined(__OpenBSD__) || defined(__APPLE__)
++#if defined(DLSYM_NEEDS_UNDERSCORE) || (defined(__OpenBSD__) && !defined(__ELF__)) || defined(__APPLE__)
+     char adj_entryname[1024];
+ #else
+ #define adj_entryname entryname
+@@ -181,7 +181,7 @@ int _sasl_locate_entry(void *library, co
+ 	return SASL_BADPARAM;
+     }
+ 
+-#if defined(DLSYM_NEEDS_UNDERSCORE) || defined(__OpenBSD__) || defined(__APPLE__)
++#if defined(DLSYM_NEEDS_UNDERSCORE) || (defined(__OpenBSD__) && !defined(__ELF__)) || defined(__APPLE__)
+     snprintf(adj_entryname, sizeof adj_entryname, "_%s", entryname);
+ #endif
+