i965/fs: Fix broken rendering in large shaders with UBO loads.

The lowering process creates a new vgrf on gen7 that should be represented
in live interval analysis.  As-is, it was getting a conflicting allocation
with gl_FragDepth in the dolphin emulator, producing broken rendering.

NOTE: This is a candidate for the 9.1 branch.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61317
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/brw_fs.cpp

@@ -2499,6 +2499,8 @@ fs_visitor::lower_uniform_pull_constant_loads()
          inst->insert_before(setup2);
          inst->opcode = FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD_GEN7;
          inst->src[1] = payload;
+
+         this->live_intervals_valid = false;
       } else {
          /* Before register allocation, we didn't tell the scheduler about the
           * MRF we use.  We know it's safe to use this MRF because nothing