wcc: defer capacity 32 with a loud cap error, both stages

wwstage capped defers at 16 and SILENTLY DROPPED the 17th; cstage
capped at 32. Align the cap at 32 and make exceeding it a loud
compile error in BOTH stages — the silent 16-vs-32 split was the bug
(a defer that never runs is a leaked resource). Both stages move in
one commit: one cap contract.

cmd/w6c/cgen.c

@@ -14725,9 +14725,11 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
 		break;
 	}
 	case N_DEFER:
-		if (ndefers < DEFER_MAX) {
-			defers[ndefers++] = n->lhs;
-		}
+		/* #40: at the cap, fail loud rather than silently drop the
+		 * deferred call (the ww twin in cgenstmt.ww fatals too). */
+		if (ndefers >= DEFER_MAX)
+			fatal("cgen: too many defers in one function");
+		defers[ndefers++] = n->lhs;
 		break;
 	case N_YIELD:
 		/* Evaluate the value into AX, then jump to the enclosing