Include src.opts.mk after SHLIBDIR has been defined so libnv is installed to
/lib , not /usr/lib

MFC after: 3 days
Approved by: rpaulo (mentor)
Submitted by: antoine
Pointyhat to: me
Phabric: D739


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271241 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f