Fix format string mistakes revealed by new checking.

An assortment of errors: int vs size_t confusion (probably undetected
since the big switchover in commit 0cda34c6f), some outright spurious
parameters after the format string (copy-paste errors), a particularly
silly one in pscp.c (a comma between two halves of what should have
been a single string literal), and a _missing_ format string in ssh.c
(but luckily in a context where the only text that would be wrongly
treated as a format string was error messages generated elsewhere in
PuTTY).

ssh2connection.c

@@ -750,7 +750,8 @@ static bool ssh2_connection_filter_queue(struct ssh2_connection_state *s)
                         "Received %s for channel %d with no outstanding "
                         "channel request",
                         ssh2_pkt_type(s->ppl.bpp->pls->kctx,
-                                      s->ppl.bpp->pls->actx, pktin->type));
+                                      s->ppl.bpp->pls->actx, pktin->type),
+                        c->localid);
                     return true;
                 }
                 ocr->handler(c, pktin, ocr->ctx);