Makefile.am, configure.ac, NEWS.adoc: implement `make install-as-root` [#1298] #2560

Job	Run time
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, no)	4m 47s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, libusb-1.0)	4m 42s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, no, libusb-0.1)	4m 43s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, no)	4m 43s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, libusb-1.0)	5m 2s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, nss, libusb-0.1)	4m 50s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, no)	4m 38s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, libusb-1.0)	4m 51s
Analyze (cpp, ubuntu-latest, CC=gcc CXX=g++, openssl, libusb-0.1)	4m 45s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, no)	4m 39s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, libusb-1.0)	4m 40s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, no, libusb-0.1)	4m 49s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, no)	4m 48s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, libusb-1.0)	4m 54s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, nss, libusb-0.1)	5m 22s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, no)	4m 36s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, libusb-1.0)	4m 55s
Analyze (cpp, ubuntu-latest, CC=clang CXX=clang++, openssl, libusb-0.1)	4m 50s
Analyze (python, ubuntu-latest, PYTHON=python3, no, no)	1m 7s
	1h 27m 41s

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