engine: look dictionaries up synchronously

The dictionary thread ran in imthread's own proc, so a lookup could
only start once the engine blocked, and it was a trie probe anyway; the
emoji and Hanja searches already called dictlookup directly. The
request/result channels, sequence numbers, staleness checks and the
second draw per Japanese key are gone; dictqjp fills the candidates
in place. Emit.dict and Lang.dictq only ever triggered lookups for
Vietnamese, which has no dictionary. dictlookup(Lang*, key, out, max)
returns the count. The Hanja lookup no longer pre-checks for a single
syllable; a reading either has an entry or it does not.

dict.c

@@ -1,52 +1,34 @@
 #include "dat.h"
 #include "fn.h"
 
-/* Candidates are the space-separated words of the value; the reading itself
- * is a candidate only for the emoji dictionary. */
-void
-dictlookup(Dictreq *req, Dictres *res)
+/*
+ * Fills out[] with up to max candidates for key: the space-separated words
+ * of the entry, minus the key itself except in the emoji dictionary, where
+ * a query may name its own answer.
+ */
+int
+dictlookup(Lang *l, Str *key, Str *out, int max)
 {
-	Lang *l;
 	char *p, *e, *sp;
 	Str tmp;
-	int vlen;
+	int n, vlen;
 
-	res->key = req->pre;
-	res->nkouho = 0;
-	res->lang = req->lang;
-	res->seq = req->seq;
-	l = getlang(req->lang);
-	if(req->key.n == 0 || l == nil ||
-	   trielookup(l->dict, &req->key, &p, &vlen) != TrieExact)
-		return;
+	if(l == nil || key->n == 0 ||
+	   trielookup(l->dict, key, &p, &vlen) != TrieExact)
+		return 0;
+	n = 0;
 	e = p + vlen;
-	while(res->nkouho < Maxkouho && p < e){
+	while(n < max && p < e){
 		while(p < e && *p == ' ')
 			p++;
 		sp = p;
 		while(p < e && *p != ' ')
 			p++;
 		if(sinit(&tmp, sp, p - sp) && tmp.n > 0 &&
-		   (req->lang == LangEMOJI || scmp(&tmp, &req->key) != 0))
-			res->kouho[res->nkouho++] = tmp;
-	}
-}
-
-void
-dictthread(void*)
-{
-	Dictreq req;
-	static Dictres res;
-
-	threadsetname("dict");
-	for(;;){
-		if(chanrecv(dictreqc, &req) < 0)
-			break;
-		while(channbrecv(dictreqc, &req) > 0)
-			;
-		dictlookup(&req, &res);
-		chansend(dictresc, &res);
+		   (l->lang == LangEMOJI || scmp(&tmp, key) != 0))
+			out[n++] = tmp;
 	}
+	return n;
 }
 
 static Trie*