i965: use nir_lower_indirect_derefs() for GLSL

This moves the nir_lower_indirect_derefs() call into
brw_preprocess_nir() so thats is called by both OpenGL and Vulkan
and removes that call to the old GLSL IR pass
lower_variable_index_to_cond_assign()

We want to do this pass in nir to be able to move loop unrolling
to nir.

There is a increase of 1-3 instructions in a small number of shaders,
and 2 Kerbal Space program shaders that increase by 32 instructions.

Shader-db results BDW:

total instructions in shared programs: 8705873 -> 8706194 (0.00%)
instructions in affected programs: 32515 -> 32836 (0.99%)
helped: 3
HURT: 79

total cycles in shared programs: 74618120 -> 74583476 (-0.05%)
cycles in affected programs: 528104 -> 493460 (-6.56%)
helped: 47
HURT: 37

LOST:   2
GAINED: 0

1 files changed, 0 insertions, 10 deletions

diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 9b65e353a90..6b0a3c97586 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -177,16 +177,6 @@ anv_shader_compile_to_nir(struct anv_device *device,
 
    nir_shader_gather_info(nir, entry_point->impl);
 
-   nir_variable_mode indirect_mask = 0;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectInput)
-      indirect_mask |= nir_var_shader_in;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectOutput)
-      indirect_mask |= nir_var_shader_out;
-   if (compiler->glsl_compiler_options[stage].EmitNoIndirectTemp)
-      indirect_mask |= nir_var_local;
-
-   nir_lower_indirect_derefs(nir, indirect_mask);
-
    return nir;
 }