glsl: Initialize lower_ubo_reference_visitor members in constructor.

Fix defects reported by Coverity Scan.

Uninitialized pointer field (UNINIT_CTOR)
uninit_member: Non-static class member buffer_access_type is not
initialized in this constructor nor in any functions that it
calls.
uninit_member: Non-static class member uniform_block is not
initialized in this constructor nor in any functions that it
calls.
uninit_member: Non-static class member progress is not initialized
in this constructor nor in any functions that it calls.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7120>

src/compiler/glsl/lower_ubo_reference.cpp

@@ -48,8 +48,10 @@ public:
    lower_ubo_reference_visitor(struct gl_linked_shader *shader,
                                bool clamp_block_indices,
                                bool use_std430_as_default)
-   : shader(shader), clamp_block_indices(clamp_block_indices),
-     struct_field(NULL), variable(NULL)
+   : buffer_access_type(ubo_load_access),
+     shader(shader), clamp_block_indices(clamp_block_indices),
+     struct_field(NULL), variable(NULL), uniform_block(NULL),
+     progress(false)
    {
       this->use_std430_as_default = use_std430_as_default;
    }