- (djm) [configure.ac regress/agent-getpeereid.sh regress/multiplex.sh]

 - (djm) [configure.ac regress/agent-getpeereid.sh regress/multiplex.sh]
   [regress/sftp-glob.sh regress/test-exec.sh] Rework how feature tests are
   disabled on platforms that do not support them; add a "config_defined()"
   shell function that greps for defines in config.h and use them to decide
   on feature tests.
   Convert a couple of existing grep's over config.h to use the new function
   Add a define "FILESYSTEM_NO_BACKSLASH" for filesystem that can't represent
   backslash characters in filenames, enable it for Cygwin and use it to turn
   of tests for quotes backslashes in sftp-glob.sh.
   based on discussion with vinschen AT redhat.com and dtucker@; ok dtucker@