ci: bump MAKEFLAGS to -j60 for ffmpeg/libva/mpv builds

distcc-avahi 3.4-19 + the ffmpeg --cc=distcc-shim landing means fermi can
actually fan compiles out across the zeroconf pool. With MAKEFLAGS="-j$(nproc)"
the runner only had ~3 outstanding TUs at a time, leaving ~57 worker slots
idle. Bump to -j60 to fill the pool (tesla 16 + dcc1 16 + dcc2 16 +
boltzmann 10 + a few local).

.gitea/workflows/build.yml

@@ -419,8 +419,9 @@ jobs:
           cp -r arch/ffmpeg-v4l2-request-git /tmp/build-ffmpeg-v4l2
           chown -R builder:builder /tmp/build-ffmpeg-v4l2
           cd /tmp/build-ffmpeg-v4l2
-          # Parallelise: fermi has 4 A55 cores; -j4 fits RAM during link.
-          sudo -u builder -H env MAKEFLAGS="-j$(nproc)" \
+          # Parallelise wide; distcc-avahi distributes compiles across the
+          # zeroconf pool (tesla, dcc1, dcc2, boltzmann ≈ 60 logical cores).
+          sudo -u builder -H env MAKEFLAGS="-j60" \
             makepkg --nocheck --noconfirm --syncdeps --cleanbuild
           ls -la *.pkg.tar.* | grep -v "\.sig$"
 
@@ -530,7 +531,7 @@ jobs:
           cp -r arch/libva-v4l2-request-fourier /tmp/build-libva-v4l2
           chown -R builder:builder /tmp/build-libva-v4l2
           cd /tmp/build-libva-v4l2
-          sudo -u builder -H env MAKEFLAGS="-j$(nproc)" \
+          sudo -u builder -H env MAKEFLAGS="-j60" \
             makepkg --nocheck --noconfirm --syncdeps --cleanbuild
           ls -la *.pkg.tar.* | grep -v "\.sig$"
 
@@ -667,7 +668,7 @@ jobs:
           cp -r arch/mpv-fourier /tmp/build-mpv
           chown -R builder:builder /tmp/build-mpv
           cd /tmp/build-mpv
-          sudo -u builder -H env MAKEFLAGS="-j$(nproc)" \
+          sudo -u builder -H env MAKEFLAGS="-j60" \
             makepkg --nocheck --noconfirm --syncdeps --cleanbuild
           ls -la *.pkg.tar.* | grep -v "\.sig$"