Consolidate WITH_XXXX feature symbols

[Aleksander Morgado]

Hey Ben, Dan and everyone,

These patches try to consolidate how the WITH_XXXX per-feature symbols are defined in the project: the symbols would only be defined when the feature is enabled.

Ben, PATCH 2/4 would be equivalent to the fix you posted.

What do you think?

  [PATCH 1/4] build: only define WITH_POLKIT if enabled
  [PATCH 2/4] build: only define WITH_SYSTEMD_JOURNAL if enabled
  [PATCH 3/4] build: WITH_UDEV is only defined when enabled
  [PATCH 4/4] build: rename --with-suspend-resume to --with-systemd-suspend-resume