intel/compiler/vec4: Switch liveness analysis to IR analysis framework

This involves wrapping vec4_live_variables in a BRW_ANALYSIS object
and hooking it up to invalidate_analysis() so it's properly
invalidated.  Seems like a lot of churn but it's fairly
straightforward.  The vec4_visitor invalidate_ and
calculate_live_intervals() methods are no longer necessary after this
change.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4012>

src/intel/compiler/brw_vec4_visitor.cpp

@@ -1841,6 +1841,7 @@ vec4_visitor::vec4_visitor(const struct brw_compiler *compiler,
      prog_data(prog_data),
      fail_msg(NULL),
      first_non_payload_grf(0),
+     live_analysis(this),
      need_all_constants_in_pull_buffer(false),
      no_spills(no_spills),
      shader_time_index(shader_time_index),
@@ -1854,8 +1855,6 @@ vec4_visitor::vec4_visitor(const struct brw_compiler *compiler,
 
    memset(this->output_num_components, 0, sizeof(this->output_num_components));
 
-   this->live_intervals = NULL;
-
    this->max_grf = devinfo->gen >= 7 ? GEN7_MRF_HACK_START : BRW_MAX_GRF;
 
    this->uniforms = 0;