Pass '-undefined- to the linker

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61663 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/ccc b/utils/ccc
index 6e42369..4142ee7 100755
--- a/utils/ccc
+++ b/utils/ccc
@@ -280,7 +280,7 @@
                    '-e', '-install_name',
                    '-unexported_symbols_list', '-exported_symbols_list', 
                    '-compatibility_version', '-current_version', '-init',
-                   '-seg1addr', '-dylib_file', '-Xlinker'):
+                   '-seg1addr', '-dylib_file', '-Xlinker', '-undefined'):
             link_opts.append(arg)
             link_opts.append(args[i+1])
             i += 1