[opamlock] fix opam.lock target
[opamlock] fix opam.lock target

Summary:
Forgot to substitute "infer" for "infer-lock-deps" and so `make opam.lock` was
failing if `infer` has not been manually pinned (which I didn't notice
previously because I had it git-pinned for some reason...).

Reviewed By: martinoluca

Differential Revision: D5310206

fbshipit-source-id: c023659

facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,ropas/infer,blzq/infer,ropas/infer,facebook/infer,ropas/infer,blzq/infer,blzq/infer,jvillard/infer,blzq/infer,blzq/infer,facebook/infer,blzq/infer,facebook/infer,jvillard/infer,facebook/infer,ropas/infer,jvillard/infer,ropas/infer,ropas/infer,jvillard/infer,facebook/infer,jvillard/infer