linux-build: POSIX branches for time()/bcopy/bzero and Win32-only probes

- pc_protos.h: the vestigial 'long long time()' prototype conflicts with
  glibc's time_t time(time_t*); no game code calls time(), guard it to
  _WIN32 (MinGW shadows <time.h> with the N64 stub; POSIX gets the real one).
- n64stubs.c: don't redefine bcopy/bzero on POSIX -- glibc exports them
  (via <strings.h>, size_t sizes); the local int-signature definitions
  conflict. _WIN32-only now.
- libultra.c: #define _GNU_SOURCE on POSIX for clock_gettime(CLOCK_*) and
  pthread_getattr_np; guard the D60 VirtualQuery committed-memory probe and
  GetCurrentThreadStackLimits behind PLATFORM_WINDOWS with a
  pthread_getattr_np-based stack-bounds fallback for the diagnostic path.

Windows build verified green.

port/include/pc_protos.h

@@ -447,7 +447,9 @@ s32 texLoadFromGdl();
 s32 texReadUncompressed();
 void texSelect();
 s32 texShrinkNonPaletted();
-long long time();
+#if defined(_WIN32)
+long long time(); /* MinGW: <time.h> is shadowed by the N64 stub here; POSIX gets the real one */
+#endif
 const char * tokenFind();
 s32 tokenReadIo();
 void transform3Dto2DWithZScaling();

port/src/libultra.c

@@ -1,3 +1,8 @@
+/* POSIX: enable clock_gettime(CLOCK_REALTIME/MONOTONIC) and pthread_getattr_np. */
+#if !defined(_WIN32) && !defined(_GNU_SOURCE)
+#define _GNU_SOURCE 1
+#endif
+
 /*
  * libultra OS shims for the PC port, plus the cooperative thread kernel.
  *
@@ -765,6 +770,7 @@ static int dramHostAddrValid(uintptr_t addr, u32 size)
      * buffers (e.g. ramrom_data_target), stack compbuffers, sidecar images.
      * Truncated wild addresses (0x40xxxxxx from s32 pointer math) are not
      * committed, so VirtualQuery still catches them. */
+#if defined(PLATFORM_WINDOWS)
     {
         MEMORY_BASIC_INFORMATION mbi;
         if (VirtualQuery((LPCVOID)addr, &mbi, sizeof(mbi)) == sizeof(mbi) &&
@@ -774,6 +780,13 @@ static int dramHostAddrValid(uintptr_t addr, u32 size)
             return 1;
     }
     return 0;
+#else
+    /* No cheap committed-memory probe on POSIX; this is a TEMP D60 diagnostic.
+     * Be permissive so legitimate .bss/stack/sidecar DMA targets are not
+     * flagged as fatal (a genuinely wild target still faults in the memcpy). */
+    (void)size;
+    return 1;
+#endif
 }
 
 static void piServiceDma(s32 direction, u32 srcPA, void *dstVA, u32 size)
@@ -817,6 +830,7 @@ static void piServiceDma(s32 direction, u32 srcPA, void *dstVA, u32 size)
                 wp += snprintf(wp, win + sizeof(win) - (wp - win),
                                " %p", (void *)sp[i]);
             }
+#if defined(PLATFORM_WINDOWS)
             {
                 PVOID tlow = NULL, thigh = NULL;
                 GetCurrentThreadStackLimits(&tlow, &thigh);
@@ -826,6 +840,22 @@ static void piServiceDma(s32 direction, u32 srcPA, void *dstVA, u32 size)
                              ((uintptr_t)dstVA >= (uintptr_t)tlow &&
                               (uintptr_t)dstVA < (uintptr_t)thigh));
             }
+#else
+            {
+                pthread_attr_t at;
+                void *sbase = NULL;
+                size_t ssize = 0;
+                if (pthread_getattr_np(pthread_self(), &at) == 0) {
+                    pthread_attr_getstack(&at, &sbase, &ssize);
+                    pthread_attr_destroy(&at);
+                }
+                sysLogPrintf(LOG_ERROR,
+                             "D60 thread stack: %p..%p  dst-in-stack=%d\n",
+                             sbase, (void *)((uintptr_t)sbase + ssize),
+                             ((uintptr_t)dstVA >= (uintptr_t)sbase &&
+                              (uintptr_t)dstVA < (uintptr_t)sbase + ssize));
+            }
+#endif
             sysLogPrintf(LOG_ERROR,
                          "D60 BAD DMA TARGET dst=%p src=0x%08X size=0x%X "
                          "stack@rbp:%s\n",

port/src/n64stubs.c

@@ -106,10 +106,14 @@ u8 (*tlbmanageGetTlbAllocatedBlock(void))[TLB_BLOCK_SIZE]
     return (u8 (*)[TLB_BLOCK_SIZE])0x70700000;
 }
 
-/* --- K&R libc helpers (IDO provided these; the host libc does not) ------- */
-/* Signatures mirror include/PR/os.h:983 / include/bstring.h exactly.        */
+/* --- K&R libc helpers (IDO provided these; MinGW's libc does not) -------- */
+/* Signatures mirror include/PR/os.h:983 / include/bstring.h exactly.
+ * glibc still exports bcopy/bzero (declared in <strings.h> with size_t), so
+ * on the POSIX port we use those and must NOT redefine them here. */
+#if defined(_WIN32)
 void bcopy(const void *src, void *dst, int n) { memmove(dst, src, (size_t)n); }
 void bzero(void *s, int n)                     { memset(s, 0, (size_t)n); }
+#endif
 
 /* --- libm internals (IDO's libm exposed these; MinGW's does not) --------- */
 /* Quiet NaN float, used by gu/cosf.c and game/zlib.c. The VALUE is the same  */