Allow `apc_modbus` instances to monitor several USB devices on the same system #2651

Job	Run time
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, no)	5m 12s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, libusb-1.0)	6m 14s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, libusb-0.1)	5m 10s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, no)	6m 28s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, libusb-1.0)	5m 1s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, libusb-0.1)	5m 53s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, no)	6m 22s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, libusb-1.0)	5m 0s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, libusb-0.1)	4m 59s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, no)	4m 59s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, libusb-1.0)	4m 57s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, libusb-0.1)	6m 18s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, no)	4m 55s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, libusb-1.0)	5m 48s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, libusb-0.1)	5m 15s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, no)	5m 2s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, libusb-1.0)	6m 32s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, libusb-0.1)	5m 9s
Analyze (python, ubuntu-latest, PYTHON=python3, no, no)	1m 10s
	1h 40m 24s

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