Library crypt is missing when installing rserve_client on MacOS

Install of rserve_client packs fails on MacOS because crypt library is missing. Removing library from the Makefile seems to resolve the issue.

mkdir -p lib/x86_64-darwin
g++   -shared -L"/usr/local/Cellar/swipl/8.1.1/lib/swipl/lib/x86_64-darwin" -o lib/x86_64-darwin/ cc/rserve.o Rserve/src/client/cxx/Rconnection.o -ldl -lcrypt -lm -lswipl
ld: library not found for -lcrypt
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [lib/x86_64-darwin/] Error 1