[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@
[regress/cipher-speed.sh regress/forcecommand.sh regress/forwarding.sh]
Sync regress tests to -current; include dtucker@'s new cfgmatch and
forcecommand tests. Add cipher-speed.sh test (not linked in yet)
Darren Tucker
Tim Rice
Damien Miller