uses poll() when a fine poll() is available, so now libcurl can be
built without select() support at all if a fine poll() is available.

and/or HAVE_VARIADIC_MACROS_GCC for specific compiler versions that support
variadic macros with C99 style and/or old gcc style in their specific config.h
file.

If previous definitions are not done, even when aplicable, and --disable-verbose
is used, the fallback (void) method will be used to define infof, avoiding the
inclusion of unwanted strings in the resulting library/executable.

recently

  A left-over bug from the February 21 fix.

one over to KNOWN_BUGS

test case 288 to verify it.

before resorting to the kill -9 hammer.

Added test harness infrastructure to support scp/sftp tests, using
OpenSSH as the server.

plus made --pass work on an SSH private key as well.

Shave off a couple of function calls in the part of
Curl_pgrsUpdate() which is always executed when called.

Fix a couple of comments.

For completeness sake, wait_ms() might also get interrupted when
experimental CURL_ACKNOWLEDGE_EINTR is defined.