glsl: Add shared variable type

Shared variables are stored in a common pool accessible by all threads
in a compute shader local work group.

These variables are similar to OpenCL's local/__local variables.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>

src/glsl/ir_print_visitor.cpp

@@ -174,7 +174,7 @@ void ir_print_visitor::visit(ir_variable *ir)
    const char *const patc = (ir->data.patch) ? "patch " : "";
    const char *const inv = (ir->data.invariant) ? "invariant " : "";
    const char *const mode[] = { "", "uniform ", "shader_storage ",
-                                "shader_in ", "shader_out ",
+                                "shader_shared ", "shader_in ", "shader_out ",
                                 "in ", "out ", "inout ",
 			        "const_in ", "sys ", "temporary " };
    STATIC_ASSERT(ARRAY_SIZE(mode) == ir_var_mode_count);