Fix openbsd compile build errors due to dependency on libiconv

The path to libiconv is selected in config/cf/OpenBSD.cf reusing the
same trick  as FreeBSD does.

cde/config/cf/OpenBSD.cf

@@ -1072,6 +1072,7 @@ CXXDEPENDINCLUDE != CcCmd -v -x c++ /dev/null -fsyntax-only \
 #define ArchitectureDefines    -DOPENBSD_ARCHITECTURE
 
 #define BuildLibPathVar        LD_LIBRARY_PATH
+ICONVSYSLIB != if test -f /usr/local/include/iconv.h; then echo -liconv; else echo; fi
 
 #ifndef KornShell
 #define KornShell               /usr/local/bin/ksh93