Fix sys-power/cpupower-gui

[seven-mile]

sys-power/cpupower-gui has two issues

• When building with meson>=0.60, fail with function does not take positional arguments
  • Meson issue reference
  • Patch command from Arch
• The typo of use flag use_libexec
  • meson_options.txt reference

I'm not familiar with ebuild repo maintaince, feel free to fix if something wrong.

[orsonteodoro]

You are close.

1. The use_libexec is not a standard global USE flag same goes with libexec.[2] The style guide prefers - over _.[1] Typically a USE flag is simple so just 1 word. One may change it to dbus or leave it as a local USE flag. Generally, global USE flag names are preferred over local names.
2. The meson_use function from the meson.eclass accepts 2 args.[3] Arg1 is the USE flag. Arg2 is the build flag. If only 1 arg is provided, it will use it as both the USE flag and the build flag.

I will let you make the change to gain experience. If you prefer not to make change, I will merge the change(s) and fix it afterward.

References:
[1] https://dev.gentoo.org/~ulm/pms/head/pms.html#section-3.1.4
[2] https://www.gentoo.org/support/use-flags/
[3] https://github.com/gentoo-mirror/gentoo/blob/stable/eclass/meson.eclass#L254

[seven-mile]

Thank you for reviewing! I pushed the fix and you can check it out.
The commit log is verbose now. Freely squash it if you like~

[orsonteodoro]

Thank you for the contribution.