... and use Curl_safefree() instead of free()

Patch-by: byte_bucket

The information about building with Kerberos4 support was half a year out
of date. We dropped support for that.

Also, combined a couple of #ifdef sections

Port number zero is perfectly allowed to connect to. I moved to storing
the remote port number in an int so that -1 means undefined and 0-65535
can be used for legitimate port numbers.

Setting the TIMER_STARTSINGLE timestamp first in CONNECT has the
drawback that for actions that go back to the CONNECT state, the time
stamp is reset and for the multi_socket API there's no corresponding
Curl_expire() then so the timeout logic gets wrong!

Reported-by: Brad Spencer
Bug: http://curl.haxx.se/mail/lib-2014-02/0036.html

... since that’s how the RFC calls it.

... as it isn't used then!

Remove slash/backslash problem, now only slashes are used,
Wmake automaticaly translate slash/backslash to proper version or tools are not sensitive for it.
Enable spaces in path.
Use internal rm command for all host platforms
Add error message if old Open Watcom version is used. Some old versions exhibit build problems for Curl latest version. Now only versions 1.8, 1.9 and 2.O beta are supported

Remove compilation message for platforms where size of long type
is equal size of int type.

Ensure a source file isn't generated for the following informational
command line parameters when --libcurl is specified:

--help, --manual, --version and --engine list

As the output would only include a fairly empty looking main() function
and a call to curl_easy_init() and curl_easy_cleanup() when performed
with --engine list.

Correctly output libcurl source code that includes multiply operations
as specified by --next. Note that each operation evaluates to a single
curl_easy_perform() in source code form.

Also note that the output could be optimised a little so global config
options are only output once rather than per operation as is presently
the case.

warning: declaration of 'struct GlobalConfig' will not be visible
outside of this function

incompatible types - from 'OperationConfig *' to 'GlobalConfig *'

For HTTP/2, we may read up everything including responde body with
header fields in Curl_http_readwrite_headers. If no content-length is
provided, curl waits for the connection close, which we emulate it
using conn->proto.httpc.closed = TRUE. The thing is if we read
everything, then http2_recv won't be called and we cannot signal the
HTTP/2 stream has closed. As a workaround, we return nonzero from
data_pending to call http2_recv.

nghttp2 has yet again extended its callback struct and this is an
attempt to make curl compile with nghttp2 from current git