[release] install symlinks as symlinks
[release] install symlinks as symlinks

Summary: The clang distribution uses symlinks in some places, which avoids copying rather large binaries. `make install` was replacing these with actual copies. Try not to be so wasteful anymore.

Reviewed By: mbouaziz

Differential Revision: D8260777

fbshipit-source-id: eccabab

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