Cmake check for LIBRT returns true on MacOS.

[jtressle]

I've been testing Glomap on a docker ubuntu system and it's been working perfectly. I just tried to compile it for MacOS and iOS, and found an issue with this check:

check_library_exists(rt shm_open "" HAVE_LIBRT)

I'm using the ios-cmake git to configure my cmake, and passing in
-DPLATFORM=MAC_ARM64
or
-DPLATFORM=OS64
for my platforms. For both cases, I'm getting HAVE_LIBRT equal to true.

I did a search and couldn't find librt on my Mac. However, I could be missing something.

I ended up replacing:

check_library_exists(rt shm_open "" HAVE_LIBRT)

with:

# Replace the single check_library_exists with:
if(APPLE)
    set(HAVE_LIBRT FALSE)
else()
    check_library_exists(rt shm_open "" HAVE_LIBRT)
endif()

Should this be updated or do I have a bad environment?

Thanks!