Handle alternatives in transaction files

[Duncaen]

No description provided.

[Duncaen]

This should resolve all issues with switching files between real and alternatives (#253).
Additionally files.plist is now loaded and added to the transaction files at the same time scripts are loaded from the binary package, instead of loading the binpkgs twice.

[lgtm-com]

This pull request fixes 1 alert when merging 121d12e into 6e3309b - view on LGTM.com

fixed alerts:

• 1 for Time-of-check time-of-use filesystem race condition

[Chocimier]

Few nits. Had not read in depth yet.

[Chocimier]

is it xbps_dictionary_copy_mutable?

[Duncaen]

xbps_dictionary_copy{,_mutable} does a shallow copy. This function copies each the keys and values, which are the alternative group provider arrays, which with a shallow copy would modify the pkgdb's alternative providers.

At the moment, this copy is used to "simulate" the alternative changes during the transaction, but it might make sense to rip out all alternative changes during extraction of packages and just do it once before running all the post install scripts.

[lgtm-com]

This pull request fixes 1 alert when merging cfa9e33 into 061f5cb - view on LGTM.com

fixed alerts:

• 1 for Time-of-check time-of-use filesystem race condition

[lgtm-com]

This pull request fixes 1 alert when merging f8d708f into 061f5cb - view on LGTM.com

fixed alerts:

• 1 for Time-of-check time-of-use filesystem race condition