[vcpkg baseline][osgearth/gdal] Re-fix dependency gdal

[JackBoosY]

The gdal requires freexl on non-Windows:

/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlsdatasource.o): In function `OGRXLSDataSource::~OGRXLSDataSource()':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:66: undefined reference to `freexl_close'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlsdatasource.o): In function `OGRXLSDataSource::Open(char const*, int)':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:147: undefined reference to `freexl_get_info'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:152: undefined reference to `freexl_select_active_worksheet'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:155: undefined reference to `freexl_get_worksheet_name'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:160: undefined reference to `freexl_worksheet_dimensions'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:171: undefined reference to `freexl_close'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlsdatasource.o): In function `OGRXLSDataSource::GetXLSHandle()':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlsdatasource.cpp:186: undefined reference to `freexl_open'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlslayer.o): In function `OGRXLSLayer::DetectHeaderLine(void const*)':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:95: undefined reference to `freexl_get_cell_value'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:105: undefined reference to `freexl_get_cell_value'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlslayer.o): In function `OGRXLSLayer::DetectColumnTypes(void const*, int*)':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:139: undefined reference to `freexl_get_cell_value'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlslayer.o): In function `OGRXLSLayer::GetLayerDefn()':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:209: undefined reference to `freexl_select_active_worksheet'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:236: undefined reference to `freexl_get_cell_value'
/mnt/vcpkg-ci/installed/x64-linux/debug/lib/libgdal.a(ogrxlslayer.o): In function `OGRXLSLayer::GetNextRawFeature()':
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:317: undefined reference to `freexl_select_active_worksheet'
/mnt/vcpkg-ci/buildtrees/gdal/x64-linux-dbg/ogr/ogrsf_frmts/xls/ogrxlslayer.cpp:324: undefined reference to `freexl_get_cell_value'

Fix this.

Since #16088 or #15808 doesn't merged, fix this issue in osgearth temporary.

[JackBoosY]

Done.

[JackBoosY]

@vicroms Ping for merge this PR.

[ras0219-msft]

Since this is a stop-gap, we should approach this with the minimal change and simply disable freexl as a dependency. This will avoid needing to change osgearth as well.