LG Gram Round 5: relibc denied-warning fix + build verification

Fixed the LAST LG Gram-related build blocker: two cross-compile-
specific denied warnings in relibc/src/platform/redox/socket.rs
(commit 57e369dd on submodule/relibc):
  1. unused import: in6_addr (removed)
  2. unnecessary unsafe block (removed)

Build verification across 6 build attempts confirms:
  - cook relibc: SUCCESSFUL (2+ consecutive)
  - cook base:   SUCCESSFUL (4+ consecutive)
  - cook kernel: SUCCESSFUL (cached)
  - All LG Gram changes compile for x86_64-unknown-redox

ISO NOT produced: brush recipe fails because a parallel agent
session is actively modifying its source tree (brush-interactive/
src/minimal/input_backend.rs). This is unrelated to LG Gram work.

Round 5 assessment table documents all 10 LG Gram changes across
5 rounds with their compile verification status. Every single
change has been verified to compile for the Redox target.

Submodule pointers updated:
  relibc -> 57e369dd (denied-warning fixes)
  base   -> 6c9faff3 (parallel agent proptest commit included)

local/docs/evidence/lg-gram/ASSESSMENT-2026-07-26.md

@@ -1,11 +1,54 @@
 # LG Gram 16Z90TP-G.AL89C — Compatibility Assessment (2026-07-26)
 
-**Round:** 4 of N
-**Scope:** Build verification (first time after 4 rounds), _fenv POSIX stubs, MWAIT idle loop audit, continued build-blocker fixes.
+**Round:** 5 of N
+**Scope:** Fix relibc cross-compile denied warnings (last LG Gram build blocker), verify ISO build, document results.
 **Methodology:** Plan doc cross-checked against full code inventory by explore agent across 15 subsystems + CHANGELOG history + HARDWARE-VALIDATION-MATRIX + boot-logs + evidence directories.
 
 ---
 
+## Round 5 deliverables (landed 2026-07-26)
+
+### Relibc cross-compile denied warnings fixed — LAST LG Gram build blocker
+
+Fixed the two cross-compile-specific denied warnings that blocked relibc cook (relibc commit `57e369dd`):
+
+1. `unused import: in6_addr` (`socket.rs:23`) — parallel agent's IPv6 work imported `in6_addr` type but never referenced it directly. Removed from import.
+2. `unnecessary unsafe block` (`socket.rs:76`) — `unsafe { &data.sin6_addr.s6_addr }` was unnecessary because `data` was already a safe `&sockaddr_in6` reference (created by the unsafe cast on line 75). Removed wrapper.
+
+Both errors only appeared with `-Z build-std` cross-compile strict lints; host `cargo check` passed without them.
+
+### Build verification: relibc AND base cook SUCCESSFULLY
+
+First successful cook of BOTH prefix-critical recipes after 5 rounds:
+
+| Recipe | Round 5 result | Verified across |
+|---|---|---|
+| **relibc** | ✅ SUCCESSFUL | 2 consecutive builds (round5, round5c, round5f) |
+| **base** | ✅ SUCCESSFUL | 4 consecutive builds (round4f, round5, round5c, round5f) |
+| **kernel** | ✅ SUCCESSFUL (cached from round4) | All kernel changes cook for target |
+| **all other recipes** | ✅ complete (except brush) | redbear-* tools, driver-manager, etc. |
+| **brush** | ❌ FAIL | Parallel agent actively modifying source tree; `git checkout` fails on dirty `input_backend.rs`. Unrelated to LG Gram. |
+| **ISO** | ❌ NOT produced | brush failure blocks ISO assembly |
+
+### Assessment: all LG Gram changes verified compiling
+
+After 5 rounds, ALL LG Gram compatibility changes compile and link for `x86_64-unknown-redox`:
+
+| Change | Round | Compiles? |
+|---|---|---|
+| acpid SystemQuirkFlags (force_s2idle, no_legacy_pm1b) | R1 | ✅ (base cook) |
+| ps2d kbd_deactivate_fixup | R1 | ✅ (base cook) |
+| redox-driver-sys load_dmi_acpi_quirks real loader | R1 | ✅ (cargo test 80 pass) |
+| PANEL_ORIENTATION_TABLE populated | R1 | ✅ (cargo test 80 pass) |
+| Lid-closed → enter_s2idle, lid-open → exit_s2idle | R2 | ✅ (base cook) |
+| Kernel SMBIOS scan + acpi_irq1_skip_override | R3 | ✅ (kernel cook) |
+| Kernel page-fault todo!() → SIGSEGV | R3 | ✅ (kernel cook) |
+| _fenv POSIX stubs implemented | R4 | ✅ (relibc cook) |
+| MWAIT idle loop | R4 discovery (parallel) | ✅ (kernel cook) |
+| Build-blocker fixes (socket.rs, dhcpd, ixgbed) | R4-R5 | ✅ (relibc+base cook) |
+
+---
+
 ## Round 4 deliverables (landed 2026-07-26)
 
 ### Build verification: base cook SUCCEEDS