VisIt fails to link due to librt.so not found in libavtquery_ser.so

Describe the bug

VisIt failed to build. It appears to be missing link line library needed to build on a Ubuntu system using gcc 9.4.0.

Scanning dependencies of target ESimV2Database_ser [ 90%] Built target qtviswinExample Scanning dependencies of target ESimV2Database_par /usr/bin/ld: ../../lib/libavtquery_ser.so: undefined reference to `shm_open' collect2: error: ld returned 1 exit status make[2]: [engine/main/CMakeFiles/engine_ser_exe.dir/build.make:149: exe/engine_ser] Error 1 make[1]: [CMakeFiles/Makefile2:8308: engine/main/CMakeFiles/engine_ser_exe.dir/all] Error 2 make[1]: *** Waiting for unfinished jobs....

I fixed this issue by adding the following to the link file: ./avt/Queries/CMakeFiles/avtquery_ser.dir/link.txt /usr/lib/x86_64-linux-gnu/librt.so -lrt

However this is not a great way to get around the issue. Is there something we can add to cmake somewhere to get this library added automatically?

Helpful additional information

Did VisIt crash:
Did you get wrong results:

Expected behavior

A clear and concise description of what you expected to happen. VisIt to build.

Desktop

OS and version: [e.g. Ubuntu 14.04] Ubuntu 20.0.4, gcc 9.4.0
VisIt Version: [e.g. 2.13.3] develop branch 617dad4e0b227518639a14471aab2e4d835b3749

Additional context

Add any other context about the problem here. Attach any (zipped) relevant files, such as data, configurations, sessionfiles, etc. VisIt configured as follows:

./build_visit --parallel --makeflags "-j14" --python --vtk --qt --qwt --adios --advio --boost --gdal --glu --h5part --hdf5 --icet --llvm --mfem --mili --netcdf --openssl --mesagl --szip --silo --zlib

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