ABI update

In order to guarantee ABI compatibility with previous versions, efivar
keeps XML descriptions of its ABI in src/libefiboot.abixml,
src/libefisec.abixml, and src/libefivar.abixmlsrc/libefivar.abixml .
For each release, these must be updated to avoid issues with any updates
to the tooling in libabigail.

This commit updates the .abixml files, which have been regenerated at
the efivar 38 tag (1753149) using libabigail-2.2-2.fc38.x86_64,
so that the current ABI can be validated with abidiff against the efivar
38 release release before tagging 39.

Signed-off-by: Peter Jones <pjones@redhat.com>