* build/instdso.sh: Fix syntax error with some sed implementations.

PR: 38108
Submitted by: Masaoki Kobayashi <masaoki techfirm.co.jp>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@389797 13f79535-47bb-0310-9956-ffa450edef68