Fix: crowned centaur infidels should be able to train riding

Centaurs usually can't train riding, since they can't ride. But, after transforming into a demon, (formerly) centaur infidels are able to ride steeds. So, they should be able to train the skill. Other infidels can get to skilled in riding, so allow that here too instead of just unrestricting it.

doc/evilhack-changelog.md

@@ -3520,4 +3520,5 @@ The following changes to date are:
   or the Hammer of the Gods
 - Fix: 'The magical energy is released!' with non-directional
   psionic wave
+- Fix: crowned centaur infidels should be able to train riding
 

src/pray.c

@@ -909,6 +909,13 @@ gcrownu()
             verbalize("Thou shalt be my vassal of suffering and terror!");
             livelog_printf(LL_DIVINEGIFT, "became the Emissary of Moloch");
             unrestrict_weapon_skill(P_TRIDENT);
+            /* unlock riding if restricted (e.g. centaur).
+               infidels can get to skilled, so don't just unrestrict it */
+            if (P_RESTRICTED(P_RIDING)) {
+                P_SKILL(P_RIDING) = P_UNSKILLED;
+                P_MAX_SKILL(P_RIDING) = P_SKILLED;
+                P_ADVANCE(P_RIDING) = 0;
+            }
             P_MAX_SKILL(P_TRIDENT) = P_EXPERT;
             if (Race_if(PM_DRAUGR)) {
                 in_hand = wielding_artifact(ART_ANGELSLAYER);