allow to use XSWIGFLAGS when needed. This in turn allows to specify XCXXFLAGS for c++ which swig does understand.

of SWIG_Python_AppendOutput, which would require an extra parameter since swig 4.3.0. /home/flk/poky/build-test/tmp/work/qemux86_64-poky-linux/u-boot/2024.10/git/arch ...