Fix segfault with STM; fixes #8035. Patch from errge.

rts/Schedule.c

@@ -2722,7 +2722,19 @@ raiseExceptionHelper (StgRegTable *reg, StgTSO *tso, StgClosure *exception)
             tso->stackobj->sp = p;
 	    return STOP_FRAME;
 
-        case CATCH_RETRY_FRAME:
+        case CATCH_RETRY_FRAME: {
+            StgTRecHeader *trec = tso -> trec;
+            StgTRecHeader *outer = trec -> enclosing_trec;
+            debugTrace(DEBUG_stm,
+                       "found CATCH_RETRY_FRAME at %p during raise", p);
+            debugTrace(DEBUG_stm, "trec=%p outer=%p", trec, outer);
+            stmAbortTransaction(cap, trec);
+            stmFreeAbortedTRec(cap, trec);
+            tso -> trec = outer;
+            p = next;
+            continue;
+        }
+
 	default:
 	    p = next; 
 	    continue;