Update build-infer.sh for Mojave
Update build-infer.sh for Mojave

Summary:
Building infer from source fails on OSX Mojave, see https://github.com/facebook/infer/issues/1026

This commit adds the fix from https://github.com/facebook/infer/issues/1026 to the build script

Reviewed By: ngorogiannis

Differential Revision: D16031929

fbshipit-source-id: 3450877f4

facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer