Introduce a XMMReg4Double class and use it in overview and warping kernel code

git-svn-id: https://svn.osgeo.org/gdal/trunk@27815 f0d54148-0727-0410-94bb-9a71ac55c965
More use of XMMReg4Double

git-svn-id: https://svn.osgeo.org/gdal/trunk@27816 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_with_coverage