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.

selfhost/cmd/wcc/cgen.ww

@@ -448,7 +448,7 @@ type enumtype = struct {
 };
 
 def LOOP_MAX: i32 = 16;
-def DEFER_MAX: i32 = 16;
+def DEFER_MAX: i32 = 32;	// #40: match cstage cgen.c DEFER_MAX (shared cap)
 
 // The SysV register-return-ABI caps — the SINGLE SSoT shared by the sret
 // classifier (sretretsize over-cap-tuple arm) AND every emit/receive site