Revert "regcomp.c: Make C-array inversion lists const"

This reverts commit 241136e0ed70738cccd6c4b20ce12b26231f30e5.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Move inversion list hdr field to SV hdr"

This reverts commit d913fb457b732da4c31d0d1b8c085989a7ecd12d.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Change, variable, fcn name"

This reverts commit 875c4e2c5193b5245da578b222e9c93aad31d93b.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Move 2 hdr inversion fields to SV hdr"

This reverts commit 4fdeca7844470c929f35857f49078db1fd124dbc.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Remove unused data structure field"

This reverts commit 4b98096221966ea01c046f4f61b2dc4f60b534b9.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Make inversion lists SVt_PVLV"

This reverts commit 2c3365de8c1168f115576a4976d067e3b911c490.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.
Revert "regcomp.c: Add a constant 0 element before inversion lists"

This reverts commit 533c4e2f08b42d977e5004e823d4849f7473d2d0.
This continues the backing out of this topic branch.  A bisect shows
that the first commit exhibiting an error is the first one in the
branch.