reduce space used by Formaline's temporary files

[Roland Haas]

Formaline creates tarballs of the source code to be included in the executable. Some of the files created are used only for the tarballs and will be recreated whenever the tarballs need updating (ie they cannot be re-used).

It is therefore possible to remove these files once the tarballs have been created freeing a couple hundred MB of disk space.

[Roland Haas]

Pull request is here: https://bitbucket.org/cactuscode/cactusutils/pull-requests/25/remove-formaline-temporary-files/diff

[Roland Haas]

Please review.

[Roland Haas]

Unless objected I will apply this after 2020-02-14.

[Roland Haas]

Applied as git hash ff8e96f "Formaline: mark tarballs as INTERMEDIATE rather than PRECIOUS" of cactusutils

[Roland Haas]

This triggered a bug in make version 3.81 that is described in #2345 and fixed in git hash 93d691f "Formaline: combine rules to make tarball and blob" of cactusutils.