Test crash on Windows if GWW mode and checksums

[ivmai]

Source: master (f9e7e5f5a)
Host: Windows 10 x64
Compiler: Open Watcom C x86 32-bit Optimizing Compiler Version 2.0 beta Dec 1 2023 01:58:57 (32-bit)
How to reproduce: wmake -f WCC_MAKEFILE check ENABLE_STATIC=1 CFLAGS_EXTRA=-DCHECKSUMS
Not reproduced if: set GC_USE_GETWRITEWATCH=0
Output (gctest):

The instruction at 0x00415308 referenced memory at 0x02d91000.
The memory could not be read.
Exception fielded by 0x00417b40
EAX=0x02d91004 EBX=0x02d92000 ECX=0x02d91000 EDX=0x00000000
ESI=0x0047f558 EDI=0x02d91000 EBP=0x00000000 ESP=0x000dfc0c
EIP=0x00415308 EFL=0x00010202 CS =0x00000023 SS =0x0000002b
DS =0x0000002b ES =0x0000002b FS =0x00000053 GS =0x0000002b
Stack dump (SS:ESP)
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