Fix warning related to format-non-iso.

[Jackie9527]

Fix the following warnings when -Wno-format-non-iso is removed.

  In file included from D:\workspace\CODE\assimp\code\AssetLib\glTF\glTFImporter.cpp:45:
  In file included from D:\workspace\CODE\assimp\code\AssetLib/glTF/glTFAsset.h:1012:
D:\workspace\CODE\assimp\code\AssetLib\glTF/glTFAsset.inl(261,36): error : 'I' length modifier is not supported by ISO
C [-Werror,-Wformat-non-iso] [D:\workspace\CODE\assimp\build-msvc-clang\code\assimp.vcxproj]
D:\workspace\CODE\assimp\include\assimp/StringUtils.h(60,22): message : expanded from macro 'AI_SIZEFMT' [D:\workspace\
CODE\assimp\build-msvc-clang\code\assimp.vcxproj]
  In file included from D:\workspace\CODE\assimp\code\AssetLib\glTF\glTFImporter.cpp:45:
  In file included from D:\workspace\CODE\assimp\code\AssetLib/glTF/glTFAsset.h:1012:
D:\workspace\CODE\assimp\code\AssetLib\glTF/glTFAsset.inl(271,36): error : 'I' length modifier is not supported by ISO
C [-Werror,-Wformat-non-iso] [D:\workspace\CODE\assimp\build-msvc-clang\code\assimp.vcxproj]
D:\workspace\CODE\assimp\include\assimp/StringUtils.h(60,22): message : expanded from macro 'AI_SIZEFMT' [D:\workspace\
CODE\assimp\build-msvc-clang\code\assimp.vcxproj]
  In file included from D:\workspace\CODE\assimp\code\AssetLib\glTF\glTFImporter.cpp:45:
  In file included from D:\workspace\CODE\assimp\code\AssetLib/glTF/glTFAsset.h:1012:
D:\workspace\CODE\assimp\code\AssetLib\glTF/glTFAsset.inl(271,51): error : 'I' length modifier is not supported by ISO
C [-Werror,-Wformat-non-iso] [D:\workspace\CODE\assimp\build-msvc-clang\code\assimp.vcxproj]
D:\workspace\CODE\assimp\include\assimp/StringUtils.h(60,22): message : expanded from macro 'AI_SIZEFMT' [D:\workspace\
CODE\assimp\build-msvc-clang\code\assimp.vcxproj]

The build script is as follows:

@echo off
setlocal
set CMAKE_HOME=D:\Tools\cmake-3.26.0-windows-x86_64
set PATH=%CMAKE_HOME%\bin;%PATH%

cmake --version
ninja --version

set SRC=%CD%

set BUILD_ROOT=%SRC%\build-msvc-clang
set BUILD_TARGET=assimp

cmake -B %BUILD_ROOT% ^
    -S %SRC% ^
    -T ClangCl ^
    -DCMAKE_INSTALL_PREFIX=install-clang ^
    -DASSIMP_BUILD_ZLIB=ON ^
    -DASSIMP_BUILD_SAMPLES=ON ^
    -DASSIMP_BUILD_DRACO=OFF ^
    -DBUILD_SHARED_LIBS=ON ^
    -DASSIMP_DOUBLE_PRECISION=OFF ^
    -DASSIMP_BUILD_ASSIMP_TOOLS=ON ^
    -DASSIMP_ASAN=OFF ^
    -DASSIMP_UBSAN=OFF ^
    -DASSIMP_BUILD_TESTS=ON

cmake --build %BUILD_ROOT% --target unit --parallel

[kimkulling]

Looks fine.

[kimkulling]

Merged, thanks for you contribution.