fixesproto4 vs. xorgproto conflict

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> I am bulk-building some packages with the recent branch on 9.0_RC1
> amd64. None of the packages using X work because they somehow all
> depend on x11/fixesproto4. However, fixesproto4 pulls in xorgproto as
> a build dependency, yet its PLISTs conflict: xorgproto already
> provides fixesproto.
> 
> Should whatever causes the fixesproto4 dependency be changed to just
> pull in xorgproto?
I'm running into the same problem on macOS 11 with XQuartz.
X11BASE is /opt/x11, bmake show-buildlink3 in pkgtools/x11-links gives:

fontconfig
    bzip2
    gettext
        iconv
    zlib
    freetype2
        bzip2
        zlib
    expat
libfontenc
    zlib
MesaLib
    libX11
        libXau
            xorgproto
        libXdmcp
        libxcb
            xcb-proto
            libXdmcp
            libXau
        xorgproto
    libXdamage
        libX11
        libXfixes
            xorgproto
            libX11
        xorgproto
    libXext
        libX11
        xorgproto
    libXfixes
    libXrandr
        libX11
        libXext
        libXrender
            xorgproto
            libX11
        xorgproto
    x11-links
    libxcb
    libxshmfence
        xorgproto
    xcb-proto
    xorgproto
    pthread
libepoxy
freetype2
glu
    MesaLib
x11-links
expat
libFS
    xorgproto
libICE
libSM
    libICE
libX11
libXScrnSaver
    libX11
    libXext
    xorgproto
libXau
libXcomposite
    xorgproto
    libX11
    libXext
    libXfixes
xcursor
    libXfixes
    libXrender
libXdamage
libXdmcp
libXext
libXfixes
libXfont
    freetype2
    libfontenc
    xorgproto
libXfont2
    freetype2
    libfontenc
    xorgproto
libXft
    fontconfig
    freetype2
    libXrender
    libX11
    xorgproto
libXinerama
    libX11
    libXext
    xorgproto
libXmu
    libX11
    libXext
    libXt
        libSM
        libX11
        xorgproto
    xorgproto
libXpm
    libX11
    xorgproto
libXpresent
    libXext
    libXfixes
    libXrandr
    xorgproto
    libX11
libXrandr
libXrender
libXres
    libX11
    libXext
    xorgproto
libXt
libXtst
    xorgproto
    libX11
    libXext
    x11-links
libXv
    libX11
    libXext
    xorgproto
libdrm
libxcb
libxshmfence
pixman
xbitmaps
xcb-proto
xcb-util
    libxcb
xkeyboard-config
xorgproto
xtrans
x11-links
pthread
Xfixes
    x11-links
    fixesproto
        xorgproto

I have no idea what's going on.