Core: fixed format specifier in ngx_realloc().

The uintptr_t is an integer type, so the solution is to either update
format specifier or cast the value to pointer.  Attempt to cast results
in compiler warning as described in comment regarding gcc 12 workaround.

src/os/unix/ngx_alloc.c

@@ -62,10 +62,10 @@ ngx_realloc(void *p, size_t size, ngx_log_t *log)
     rp = realloc(p, size);
     if (rp == NULL) {
         ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
-                      "realloc(%p, %uz) failed", ptr, size);
+                      "realloc(%0uXi, %uz) failed", ptr, size);
     }
 
-    ngx_log_debug3(NGX_LOG_DEBUG_ALLOC, log, 0, "realloc: %p:%uz (prev: %p)",
+    ngx_log_debug3(NGX_LOG_DEBUG_ALLOC, log, 0, "realloc: %p:%uz (prev: %0uXi)",
                    rp, size, ptr);
 
     return rp;