Merge pull request #10742 from poettering/c-utf8

default to C.UTF-8 locale, and many improvements to env var file parsing/kernel cmdline parsing

diff --cc src/basic/exec-util.c
Simple merge

diff --cc src/basic/fileio.c
Simple merge

diff --cc src/basic/fileio.h
Simple merge

diff --cc src/locale/localectl.c
Simple merge

diff --cc src/portable/portablectl.c
Simple merge

diff --cc src/systemctl/systemctl.c
Simple merge