autoupdate: replace obsolete macros AC_HELP_STRING

- AC_HELP_STRING by AS_HELP_STRING
  https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.72/autoconf.html#index-AC_005fHELP_005fSTRING-1
Except for the ifdef in lib-prefix.m4, make the defun of AC_LIB_ARG_WITH
unconditional.
7 files changed