wcc/cgen: #94 def-array indexed &-base leg (both-stage)

`&D[i]` over a module-level DEF array SEGV'd on BOTH stages: the
TK_AMP N_INDEX N_IDENT base classify checked only the local and let
legs, so a def-array base fell to a wrong else — cstage zero-based
the addend (XORQ BX,BX -> wild pointer, cgen.c) while wwstage
value-loaded the symbol (MOVQ name(SB) = D[0], not its address,
cgenexpr.ww complex-base fallback). Divergent asm, both wild.

Add one def-array leg per stage, mirroring the working let leg:
- cs: `def_isarraydef(base) -> LEAQ name(SB),BX` alongside let_islet.
- ww: the `defvartnode` fallback the read-side cgindex already takes
  (cgenexpr.ww:1762) -> N_TARRAY classifies isglobalarr -> LEAQ
  name(SB).
The def DATA symbol already exists (plain &D + D[i]-read work), so
once the base is the address the existing i*esz scale + ADDQ
round-trips. cs and ww now emit BYTE-IDENTICAL LEAQ-SB asm — the
both-broken -> both-correct convergence is the point (#263 class).

Rows (944_def_amp_idx_run, all 0/0 byte-id): amp_int [3]int,
amp_u32 [3]u32 esz=4 (narrow scale), amp_arg &D[2] as a func-arg;
controls ctrl_plain (&D), ctrl_read (D[i]), ctrl_2d (&M[1][1]) keep
working. *p spelled `let v: T = *p` — `*p: T` parses as `*(p: T)`.

OUT (filed #112): &D[..] slicing a def-array is a distinct parse
reject needing a Hare-fidelity ruling — not this leg.

Makefile

@@ -308,6 +308,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_alias_idx_family_run \
 	  $(BIN)/test_alias_amp_idx_run \
 	  $(BIN)/test_alias_def_addr_run \
+	  $(BIN)/test_def_amp_idx_run \
 	  $(BIN)/test_alias_global_decl_run \
 	  $(BIN)/test_alias_cgen_b5_run \
 	  $(BIN)/test_alias_cgen_b6_run \
@@ -1504,6 +1505,12 @@ $(BIN)/test_alias_def_addr_run: test/wcc/944_alias_def_addr_run.c \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_def_amp_idx_run: test/wcc/944_def_amp_idx_run.c \
+		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
+		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 $(BIN)/test_alias_global_decl_run: test/wcc/944_alias_global_decl_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \