BAIL_OUT when unable to load C::AC

- no suitable test can be done without ...
prove only the executable part (hopefully).

Let's wait whether someone has one of it in a path with a
space in any directory name :D
fix spelling typo
add pkg-config check for cflags/libs
update MANIFEST and introduce reasonable SKIP-File
add Changes for 0.23 and reformat Changes
fix typo for Perl 5.006 bundled EU::MM