clock_gettime not found on macOS

I'm trying to build on macOS, but since the latest librt changes (39dba4cd) I'm not able to.

Checking for function "clock_gettime" : NO
Library rt found: NO
Checking for function "clock_gettime" with dependency -lrt: NO

tools/meson.build:39:12: ERROR: Problem encountered: clock_gettime not found

I'm targeting OS X 10.10, where I don't believe clock_gettime() is available.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information