meson: X11 dependency is automagic
Submitted by Quentin Glidic @sardemff7
Link to original bug (#794873)
Description
In commit f38e3e2c, the X11 dependency was made optional… in the check function. If you do not want to build the X11 helper library, you can simply use -Dx11=false. Having this change (f38e3e2c) was wrong, introducing an automagic dependency. If for some reason, the libX11 package is faulty, the gdk-pixbuf build will simply ignore the -Dx11=true that the package manager added to build it, resulting in a wrong gdk-pixbuf package state, making other packages fail while gdk-pixbuf should have refused to build altogether.
There are three possible solutions: simply tell Windows people to pass -Dx11=false, use a true/false/auto scheme for the option (default to "auto", "true" forces the dep, "false" force-disable the library) or have a Windows-specific test along with get_option('x11').