swayfx: update to 0.6; scenefx: update to 0.5; mangowc: update to 0.17.4

[juandmcr]

Updates for swayfx to 0.6, scenefx to 0.5 and mangowc to 0.17.4.

Swayfx 0.6 and mangowc 0.17.4 both require scenefx 0.5 and wlroots 0.20, so all three packages can be updated together. This unblocks the previous PRs (#61453, #62127) that were waiting for swayfx to support the new scenefx.

Scenefx 0.5 introduces a musl build regression that is fixed by a small patch from the Gentoo's guru overlay.

Testing the changes

• I tested the changes in this PR: YES
• I have tested mangowc 0.17.4 as my daily window manager on x86_64 (glibc) for a while now, with scenefx 0.5 as its dependency.
• I have tested swayfx 0.6 on x86_64 (glibc) with native Wayland, XWayland (Proton games), a desktop shell, and various software and customization.

Local build testing

• I built this PR locally for my native architecture, x86_64 (glibc)
• I built this PR locally for these architectures (if supported. mark crossbuilds):
  • x86_64 (glibc)
  • x86_64-musl
  • i686 (glibc)
  • aarch64 (glibc, crossbuild)
  • aarch64-musl (crossbuild)
  • armv6l (glibc, crossbuild)
  • armv6l-musl (crossbuild)
  • armv7l (glibc, crossbuild)
  • armv7l-musl (crossbuild)

Builds for i686-musl and riscv64/riscv64-musl fail due to a libjpeg-turbo (a dependency) build issue that is probably unrelated to these packages.

[juandmcr]

Just applied all the requested changes:

• Using the upstream patch 84648eb now
• Removed the patch arg, post patch from the Gentoo patch (it generated .orig files, upstream doesn't), and the comments
• Removed the empty line in the swayfx template

Also rebuilt and tested the packages on my machine.
Thanks for the review