The Linux native reliability job stopped compiling mpv_player.cc: the
node-conversion builder exposed a leaf named `Bool`, and X11's Xlib.h —
reached through epoxy/egl.h -> EGL/eglplatform.h — defines `Bool` as a
macro for `int`, so the declaration was rewritten into nonsense.
Renames that leaf to `Boolean` across the shared walk and all three
builders. The name is the only thing that changes; no conversion
behaviour differs.
edde746
35f7a12d7c