builder/module: Drop some unreachable code
builder/module: Drop some unreachable code

use_builddir is TRUE if meson is TRUE, so there can never be a meson
case in the !use_builddir case.

Coverity issue: 1452428

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>

matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,handsome-feng/flatpak,flatpak/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak