cleanup: [tcpip] prune ee lwipopts.h entries that restate lwIP 2.0.3 defaults

Symmetric with the earlier iop lwipopts.h prune. Remove seven
defines from ee/network/tcpip/src/include/lwipopts.h that either
match lwIP 2.0.3's defaults in opt.h or configure dead
subsystems, and drop the no-op #ifndef guard:

- NO_SYS=0 (default 0)
- SYS_LIGHTWEIGHT_PROT=1 (default 1)
- SLIPIF_THREAD_STACKSIZE/PRIO (slipif.c not compiled)
- PPP_THREAD_STACKSIZE/PRIO (symbols not referenced anywhere in
  lwIP 2.0.3)
- #ifndef LWIP_TCPIP_CORE_LOCKING_INPUT guard around
  MEMP_NUM_TCPIP_MSG_INPKT (LWIP_TCPIP_CORE_LOCKING_INPUT is
  defined later in the same file, so the guard never activates)

Keep MEM_LIBC_MALLOC=1 (EE deliberately overrides the default 0
to reuse newlib's malloc) and MEMP_NUM_TCPIP_MSG_API=50 (differs
from default 8).

Proof of no-op: 31/35 object files are byte-identical; the 4 that
differ (ps2ip.o, sys_arch.o, ps2ip_ps2sdk.o, erl-support.o) only
diverge in LTO-specific sections (.gnu.lto_*, .gnu.debuglto_*),
while their .text, .data and .rodata are byte-identical.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: fjtrujy

ee/network/tcpip/src/include/lwipopts.h

@@ -4,12 +4,6 @@
 #ifndef __LWIPOPTS_H__
 #define __LWIPOPTS_H__
 
-/**
- * NO_SYS==1: Provides VERY minimal functionality. Otherwise,
- * use lwIP facilities.
- */
-#define NO_SYS		0
-
 #define LWIP_TIMEVAL_PRIVATE 0
 
 /* ---------- Thread options ---------- */
@@ -41,43 +35,16 @@
  */
 #define TCPIP_THREAD_PRIO		DEFAULT_THREAD_PRIO
 
-/**
- * SLIP_THREAD_STACKSIZE: The stack size used by the slipif_loop thread.
- * The stack size value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#define SLIPIF_THREAD_STACKSIZE		DEFAULT_THREAD_STACKSIZE
-
-/**
- * SLIPIF_THREAD_PRIO: The priority assigned to the slipif_loop thread.
- * The priority value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#define SLIPIF_THREAD_PRIO		DEFAULT_THREAD_PRIO
-
-/**
- * PPP_THREAD_STACKSIZE: The stack size used by the pppInputThread.
- * The stack size value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#define PPP_THREAD_STACKSIZE		DEFAULT_THREAD_STACKSIZE
-
-/**
- * PPP_THREAD_PRIO: The priority assigned to the pppInputThread.
- * The priority value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#define PPP_THREAD_PRIO			DEFAULT_THREAD_PRIO
-
 /*
    ------------------------------------
    ---------- Memory options ----------
    ------------------------------------
 */
 /**
- * MEM_LIBC_MALLOC==1: Use malloc/free/realloc provided by your C-library
- * instead of the lwip internal allocator. Can save code size if you
- * already use it.
+ * MEM_LIBC_MALLOC==1: Use malloc/free/realloc provided by the C-library
+ * instead of lwIP's internal allocator. Default is 0; enabled on EE
+ * because newlib's malloc is already linked in and the heap pool is
+ * cheaper than a duplicate lwIP heap.
  */
 #define MEM_LIBC_MALLOC		1
 
@@ -115,12 +82,11 @@
 /**
  * MEMP_NUM_TCPIP_MSG_INPKT: the number of struct tcpip_msg, which are used
  * for incoming packets.
- * (only needed if you use tcpip.c)
+ * SP193: this should be around the size of the TCP window because the
+ * TCPIP thread may take a while to execute (non-preemptive multitasking),
+ * otherwise incoming frames may get dropped.
  */
-//SP193: this should be around the size of the TCP window because the TCPIP thread may take a while to execute (non-preemptive multitasking), otherwise incoming frames may get dropped.
-#ifndef LWIP_TCPIP_CORE_LOCKING_INPUT
 #define MEMP_NUM_TCPIP_MSG_INPKT	50
-#endif
 
 /**
  * MEMP_NUM_TCPIP_MSG_API: the number of struct tcpip_msg, which are used
@@ -146,13 +112,6 @@
  */
 #define LWIP_TCPIP_CORE_LOCKING_INPUT	1
 
-/** SYS_LIGHTWEIGHT_PROT
- * define SYS_LIGHTWEIGHT_PROT in lwipopts.h if you want inter-task protection
- * for certain critical regions during buffer allocation, deallocation and
- * memory allocation and deallocation.
- */
-#define SYS_LIGHTWEIGHT_PROT	1
-
 /*
    ---------------------------------
    ---------- TCP options ----------