multi: Change curl_multi_wait/poll to error on negative timeout

- Add new error CURLM_BAD_FUNCTION_ARGUMENT and return that error when
  curl_multi_wait/poll is passed timeout param < 0.

Prior to this change passing a negative value to curl_multi_wait/poll
such as -1 could cause the function to wait forever.

Reported-by: hamstergene@users.noreply.github.com

Fixes https://github.com/curl/curl/issues/4763

Closes https://github.com/curl/curl/pull/4765

docs/libcurl/libcurl-errors.3

@@ -147,7 +147,7 @@ Function not found. A required zlib function was not found.
 .IP "CURLE_ABORTED_BY_CALLBACK (42)"
 Aborted by callback. A callback returned "abort" to libcurl.
 .IP "CURLE_BAD_FUNCTION_ARGUMENT (43)"
-Internal error. A function was called with a bad parameter.
+A function was called with a bad parameter.
 .IP "CURLE_INTERFACE_FAILED (45)"
 Interface error. A specified outgoing interface could not be used. Set which
 interface to use for outgoing connections' source IP address with
@@ -299,6 +299,8 @@ second time. (Added in 7.32.1)
 An API function was called from inside a callback.
 .IP "CURLM_WAKEUP_FAILURE (9)"
 Wakeup is unavailable or failed.
+.IP "CURLM_BAD_FUNCTION_ARGUMENT (10)"
+A function was called with a bad parameter.
 .SH "CURLSHcode"
 The "share" interface will return a CURLSHcode to indicate when an error has
 occurred.  Also consider \fIcurl_share_strerror(3)\fP.

docs/libcurl/symbols-in-versions

@@ -334,6 +334,7 @@ CURLMSG_DONE                    7.9.6
 CURLMSG_NONE                    7.9.6
 CURLM_ADDED_ALREADY             7.32.1
 CURLM_BAD_EASY_HANDLE           7.9.6
+CURLM_BAD_FUNCTION_ARGUMENT     7.69.0
 CURLM_BAD_HANDLE                7.9.6
 CURLM_BAD_SOCKET                7.15.4
 CURLM_CALL_MULTI_PERFORM        7.9.6