i965/cfg: Fix cfg_t::dump() when a block has no immediate dominator.
i965/cfg: Fix cfg_t::dump() when a block has no immediate dominator.

Switch statements introduce a bogus loop with an unconditional break at
the end of the loop, just before the while...so the while is unreachable
and has no immediate dominator.

v2: With less exuberance

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler