Fin: fix probable_AS inflection

Model `todennäköinen` as a compound so its final component controls vowel harmony. Keep `compoundA.p` empty unless the wrapped adjective has prefix-only modifying use.

src/finnish/LexiconFin.gf

@@ -148,8 +148,7 @@ lin
   play_V2 = mkV2 (mkV "pelata") cpartitive ; --- leikkiä, soittaa
   policeman_N = mkN "poliisi" ;
   priest_N = mkN "pappi" ;
-  probable_AS = mkAS --- for vowel harmony
-    (mkA (mkN "todennäköinen") "tonennäköisempi" "todennäköisin") ; ---- sta
+  probable_AS = mkAS (compoundA "toden" (mkA "näköinen")) ;
   queen_N = mkN "kuningatar" ;
   radio_N = mk2N "radio" "radioita" ;
   rain_V0 = mkV0 (mk2V "sataa" "satoi") ;

src/finnish/ParadigmsFin.gf

@@ -221,7 +221,15 @@ oper
     = \s -> lin A {s = \\_,_ => s ; h = Back ; p = [] ; hasPrefix = False} ; ----- stemming adds bogus endings
 
   compoundA : Str -> A -> A  -- prefix glued to adjective, e.g. "hevos"+"vetoinen"
-    = \s,a -> lin A {s = \\d,c => s + a.s ! d ! c  ; h = a.h ; p = s + a.p ; hasPrefix = a.hasPrefix} ;
+    = \s,a -> lin A {
+      s = \\d,c => s + a.s ! d ! c ;
+      h = a.h ;
+      p = case a.hasPrefix of {
+        True => s + a.p ;
+        False => []
+        } ;
+      hasPrefix = a.hasPrefix
+      } ;
 
   prefixA : Str -> A -> A -- in modifying use, an uninflected glued prefix, e.g. "sähkö" for "sähköinen"
     = \pr,a -> a ** {