Round 2 of remove unused DECLS from src/libudev/{ioprio,log,macro,set,strv}

Remove the following unused DECLS:

  IOPRIO_BITS
  IOPRIO_CLASS_SHIFT
  IOPRIO_PRIO_MASK
  IOPRIO_PRIO_CLASS
  IOPRIO_PRIO_DATA
  IOPRIO_PRIO_VALUE
  ioprio_valid
  IOPRIO_BE_NR
  IOPRIO_WHO_PROCESS
  IOPRIO_WHO_PGRP
  IOPRIO_WHO_USER
  MESSAGE_ID
  EXIT_TEST_SKIP
  XSTRINGIFY
  STRINGIFY
  ALIGN_PTR
  ALIGN4_PTR
  ALIGN8_PTR
  MAX
  MAX3
  MIN
  CLAMP
  zero
  CHAR_TO_STR
  VA_FORMAT_ADVANCE
  SET_FLAG
  SET_FOREACH
  SET_FOREACH_BACKWARDS
  STRV_FOREACH_BACKWARDS
  STRV_FOREACH_PAIR
  _unused_
  _destructor_
  _deprecated_
  _weak_
  _hidden_
  _weakref_
  _introspect_
  _alignas_

Remove the following unused static inline functions:

  static inline int ioprio_set
  static inline int ioprio_get
  static inline const char* STRV_IFNOTNULL

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>