Using clang

$ CC=clang make
clang -Wall -Werror -g -lvirt -o memory_coordinator memory_coordinator.c

$ file memory_coordinator
memory_coordinator: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=3c7d8ae680abbe23b6b030479aee4c95a19dfbf6, for GNU/Linux 3.2.0, with debug_info, not stripped

Using gcc

$ CC=gcc make 
gcc -Wall -Werror -g -lvirt -o memory_coordinator memory_coordinator.c
/usr/bin/ld: /tmp/cc0UKDfy.o: in function `getHostMemoryStats':
/omscs/aos/src/project1/memory/memory_coordinator.c:8: undefined reference to `virNodeGetMemoryStats'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:10: undefined reference to `virNodeGetMemoryStats'
/usr/bin/ld: /tmp/cc0UKDfy.o: in function `getDomainMemoryStats':
/omscs/aos/src/project1/memory/memory_coordinator.c:20: undefined reference to `virDomainMemoryStats'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:42: undefined reference to `virDomainSetMemory'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:46: undefined reference to `virDomainSetMemory'
/usr/bin/ld: /tmp/cc0UKDfy.o: in function `main':
/omscs/aos/src/project1/memory/memory_coordinator.c:53: undefined reference to `virConnectOpen'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:62: undefined reference to `virConnectListAllDomains'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:65: undefined reference to `virDomainGetName'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:67: undefined reference to `virDomainGetInfo'
/usr/bin/ld: /omscs/aos/src/project1/memory/memory_coordinator.c:78: undefined reference to `virConnectClose'
collect2: error: ld returned 1 exit status
make: *** [Makefile:7: memory_coordinator] Error 1

$ gcc --version
gcc (Ubuntu 9.2.1-9ubuntu2) 9.2.1 20191008
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.