Fix #include <windows.h>

[dg0yt]

Inclusion must take place in top-level scope.

[dg0yt]

Fixes arm64 windows builds issue in vcpkg.

FAILED: Source/Common/CMakeFiles/gdcmCommon.dir/gdcmFilename.cxx.obj 
C:\PROGRA~1\MICROS~1\2022\ENTERP~1\VC\Tools\MSVC\1441~1.341\bin\Hostx64\arm64\cl.exe   /TP -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -DgdcmCommon_EXPORTS -ID:\installed\arm64-windows\include -ID:\b\gdcm\arm64-windows-dbg\Source\Common -ID:\b\gdcm\src\v3.0.24-5d851b30d1.clean\Source\Common -ID:\b\gdcm\src\v3.0.24-5d851b30d1.clean\Source\DataStructureAndEncodingDefinition -ID:\b\gdcm\arm64-windows-dbg\Testing\Source\Data -ID:\b\gdcm\src\v3.0.24-5d851b30d1.clean\Testing\Source\Data -ID:\b\gdcm\src\v3.0.24-5d851b30d1.clean\Utilities /nologo /DWIN32 /D_WINDOWS /utf-8 /GR /EHsc /MP  /D_DEBUG /MDd /Z7 /Ob0 /Od /RTC1 /showIncludes /FoSource\Common\CMakeFiles\gdcmCommon.dir\gdcmFilename.cxx.obj /FdSource\Common\CMakeFiles\gdcmCommon.dir\ /FS -c D:\b\gdcm\src\v3.0.24-5d851b30d1.clean\Source\Common\gdcmFilename.cxx
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9715): error C2664: 'unsigned int gdcm::_InterlockedIncrement(volatile unsigned int *)': cannot convert argument 1 from 'volatile long *' to 'volatile unsigned int *'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9715): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9711): note: see declaration of 'gdcm::_InterlockedIncrement'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9715): note: while trying to match the argument list '(volatile long *)'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): error C2665: 'gdcm::_InterlockedIncrement': no overloaded function could convert all the argument types
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9720): note: could be 'unsigned long gdcm::_InterlockedIncrement(volatile unsigned long *)'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): note: 'unsigned long gdcm::_InterlockedIncrement(volatile unsigned long *)': cannot convert argument 1 from 'volatile long *' to 'volatile unsigned long *'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9711): note: or       'unsigned int gdcm::_InterlockedIncrement(volatile unsigned int *)'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): note: 'unsigned int gdcm::_InterlockedIncrement(volatile unsigned int *)': cannot convert argument 1 from 'volatile long *' to 'volatile unsigned int *'
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\um\winbase.h(9724): note: while trying to match the argument list '(volatile long *)'
...

(Note the unexpected gdcm:: prefix.)