shutdown: complain if process excluded from killing spree runs of the same rootfs as PID1

core: add valgrind helper for daemon-reexec Inspired by https://github.com/systemd/systemd/issues/2187#issuecomment-165587140

basic: include only what we use This is a cleaned up result of running iwyu but without forward declarations on src/basic.

tree-wide: sort includes in *.h This is a continuation of the previous include sort patch, which only sorted for .c files.

process-util: move a couple of process-related calls over

process-util: rename get_parent_of_pid() → get_process_ppid() In order to match the other get_process_xyz() calls.

process-util: actually move rename_process() over The prototype was moved long ago, actually move the definition over now, too.

process-util: move PID related macros from macro.h to process-util.h

util-lib: move is_main_thread() to process-util.[ch]

process-util: move more process related calls to process-util.[ch]

build-sys: split internal basic/ library from shared/ basic/ can be used by everything cannot use anything outside of basic/ libsystemd/ can use basic/ cannot use shared/ shared/ can use libsystemd/