MonetDB mercurial source doesn't compile on macOS Mojave

Dear all, When trying to compile the MonetDB mercurial source on macOS Mojave, it ends with the error: /Users/jennie/monet/Apr2019/common/stream/stream.c:819:10: error: implicit declaration of function 'fdatasync' is invalid in C99 [-Werror,-Wimplicit-function-declaration] && fdatasync(fileno(fp)) < 0 ^ 1 error generated. Does anyone know a fix or workaround for this? Thanks a lot! Jennie