Merge branch 'ps/sane-ctype-workaround'

Our <sane-ctype.h> header file relied on that the system-supplied
<ctype.h> header is not later included, which would override our
macro definitions, but "amazon linux" broke this assumption.  Fix
this by preemptively including <ctype.h> near the beginning of
<sane-ctype.h> ourselves.

* ps/sane-ctype-workaround:
  sane-ctype: fix compiler error on Amazon Linux 2