Support demand paging via closures and seh

Reverts 12a79192ee which exploits normal tcg mechanism

This uses a trampoline to pass extra data to seh handlers

qemu/include/sysemu/os-win32.h

@@ -28,6 +28,7 @@
 
 #include <winsock2.h>
 #include <windows.h>
+#include <winnt.h> // For vectorized handler
 #include <ws2tcpip.h>
 
 #if defined(_WIN64)

qemu/include/tcg/tcg.h

@@ -35,11 +35,6 @@
 #include "tcg-apple-jit.h"
 #include "qemu/int128.h"
 
-// Unicorn: Default region size for win32
-#if defined(_WIN32) && !defined(WIN32_QEMU_ALLOC_BUFFER)
-#define UC_TCG_REGION_PAGES_COUNT (128) // Note less pages may cause unexpected and subtle errors.
-#endif
-
 /* XXX: make safe guess about sizes */
 #define MAX_OP_PER_INSTR 266