xash3d: remove configure option --disable-vgui

[7Ji]

the option --disable-vgui was removed from xash3d's configure script, with the option the configure script will break

removed the option and the build issue is fixed

[7Ji]

@shantigilbert
This is the last PR that's needed to fix all build issues on project Amlogic-ng. Along with #1177, #1178, #1180, they should all be merged to ensure Amlogic-ng could be built successfully.

[shantigilbert]

@shantigilbert This is the last PR that's needed to fix all build issues on project Amlogic-ng. Along with #1177, #1178, #1180, they should all be merged to ensure Amlogic-ng could be built successfully.

Thank you!