Added include <libxml/xmlsave.h> to allow build with libxml 2.12.0.

Signed-off-by: Tomasz Kłoczko <kloczek@github.com>

* fix building with libxml 2.12.0

Co-authored-by: Colomban Wendling <hypra@ban.netlib.re>

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Signed-off-by: Tomasz Kłoczko <kloczek@github.com>
Co-authored-by: raveit65 <mate@raveit.de>
Co-authored-by: Colomban Wendling <hypra@ban.netlib.re>

find . \( -name '*.h' -o -name '*.c' \) -exec sed -i 's/[[:space:]]*$//' {} \;
find . \( -name '*.h' -o -name '*.c' \) -exec sed -i 's/\t*$//' {} \;