Documentation: properly document ARES_ECANCELLED

This commit clarifies the behaviour of ares_cancel() with respect to
callbacks and adds missing documentation of ARES_ECANCELLED to the man
pages of the affected functions.

ares_cancel.3

@@ -28,7 +28,9 @@ name service channel identified by \fIchannel\fP.  \fBares_cancel\fP invokes
 the callbacks for each pending query on the channel, passing a status of
 .BR ARES_ECANCELLED .
 These calls give the callbacks a chance to clean up any state which
-might have been stored in their arguments.
+might have been stored in their arguments. If such a callback invocation adds
+a new request to the channel, that request will \fInot\fP be cancelled by the
+current invocation of \fBares_cancel\fP.
 .SH SEE ALSO
 .BR ares_init (3)
 .BR ares_destroy (3)

ares_gethostbyaddr.3

@@ -70,6 +70,9 @@ was not found.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel

ares_gethostbyname.3

@@ -74,6 +74,9 @@ was not found.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel

ares_getnameinfo.3

@@ -109,6 +109,9 @@ was not found.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel

ares_query.3

@@ -118,6 +118,9 @@ No name servers could be contacted.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel

ares_search.3

@@ -119,6 +119,9 @@ No name servers could be contacted.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel

ares_send.3

@@ -73,6 +73,9 @@ No name servers could be contacted.
 .B ARES_ENOMEM
 Memory was exhausted.
 .TP 19
+.B ARES_ECANCELLED
+The query was cancelled.
+.TP 19
 .B ARES_EDESTRUCTION
 The name service channel
 .I channel