[FYI] Merge branch 'maint' into master

[Stefano Lattarini]

commit 65643c8d626b2d60608300ad8495f1dfba1006a4
Merge: 1ffdec4 9f21b55
Author: Stefano Lattarini <address@hidden>
Date:   Sat May 11 01:06:58 2013 +0200

    Merge branch 'maint'

    * maint:
      options: try to report as much errors as possible
      warns: don't tell AM_PROG_MKDIR_P is going to be removed
      refactor: fix few "inverted boolean" usages
      options: better name for an internal function
      options: more consistency in use of return statuses to report errors
      options: tiny simplification in dealing with erroneous opts
      options: consistently use return statuses to report errors
      options: re-enable some sanity checks
      THANKS: update Eric Blake's e-mail address
      NEWS: typofix

    Signed-off-by: Stefano Lattarini <address@hidden>