Sort Makefile inputs to make build reproducible

[davidpolverari]

Some Linux distributions (such as Debian [1]) are striving to make their
build reproducible.

The usage of filesystem globbing as an input to the make build might
cause inconsistencies due to differences between locales [2]. This
inconsistent behavior prevents reproducible builds.

This patch sorts the Makefile inputs to ensure they will be always
processed in the same order [3], contributing to the build system
reproducibility.

[1] https://wiki.debian.org/ReproducibleBuilds
[2] https://reproducible-builds.org/docs/stable-inputs/#fn:sorted-wildcard
[3] https://reproducible-builds.org/docs/stable-inputs/

[merces]

Thanks! Count on us to make pev as easy as we can for packaging. 🙌

[davidpolverari]

Thanks! Count on us to make pev as easy as we can for packaging. raised_hands

Thanks a lot! :)