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

Remove eight defines from iop/tcpip-base/lwipopts.h that either
exactly match lwIP 2.0.3's own defaults in opt.h, or configure
dead subsystems that aren't compiled in this build:

- NO_SYS=0 (default 0)
- MEM_LIBC_MALLOC=0 (default 0)
- MEMP_NUM_TCPIP_MSG_API=8 (default 8)
- 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)

Also drop the no-op #ifndef LWIP_TCPIP_CORE_LOCKING_INPUT guard
around MEMP_NUM_TCPIP_MSG_INPKT; the symbol is always set later
in this same file so the guard never activates.

Proof of no-op: installed ps2ip-nm.irx SHA is unchanged
(c298b3cc2be09636c68ddd2ff077a62f2b2aa03c) before and after.

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

Author: fjtrujy

iop/tcpip/tcpip-base/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 ---------- */
@@ -41,46 +35,11 @@
  */
 #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.
- */
-#define MEM_LIBC_MALLOC		0 //FJTRUJY disable it for IOP
-
 /* MEM_ALIGNMENT: should be set to the alignment of the CPU for which
    lwIP is compiled. 4 byte alignment -> define MEM_ALIGNMENT to 4, 2
    byte alignment -> define MEM_ALIGNMENT to 2. */
@@ -131,20 +90,11 @@
 /**
  * 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.
-#ifndef LWIP_TCPIP_CORE_LOCKING_INPUT
-#define MEMP_NUM_TCPIP_MSG_INPKT        24
-#endif
-
-/**
- * MEMP_NUM_TCPIP_MSG_API: the number of struct tcpip_msg, which are used
- * for callback/timeout API communication.
- * (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 MEM_SIZE (in PBUFs), to prevent transmissions from being potentially being dropped.
-#define MEMP_NUM_TCPIP_MSG_API		8
+#define MEMP_NUM_TCPIP_MSG_INPKT	24
 
 /**
  * MEMP_NUM_NETCONN: the number of struct netconns.
@@ -167,13 +117,6 @@
  */
 #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 ----------