glsl: Hide many classes local to individual .cpp files in anon namespaces.

This gives the compiler the chance to inline and not export class symbols
even in the absence of LTO.  Saves about 60kb on disk.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@.intel.com>

src/glsl/lower_named_interface_blocks.cpp

@@ -65,6 +65,8 @@
 #include "ir_rvalue_visitor.h"
 #include "program/hash_table.h"
 
+namespace {
+
 class flatten_named_interface_blocks_declarations : public ir_rvalue_visitor
 {
 public:
@@ -83,6 +85,8 @@ public:
    virtual void handle_rvalue(ir_rvalue **rvalue);
 };
 
+} /* anonymous namespace */
+
 void
 flatten_named_interface_blocks_declarations::run(exec_list *instructions)
 {