glsl: Rename class variable_entry to ir_variable_refcount_entry.

Exporting a publicly visible class with a generic name like
"variable_entry" via ir_variable_refcount.h is kind of mean.

Many IR transformers would like to define their own "variable_entry"
class.  If they accidentally include this header, the compiler/linker
may get confused and try to instantiate the wrong variable_entry class,
leading to bizarre runtime crashes.

The hope is that renaming this one will allow .cpp files to safely
declare and use their own file-scope "variable_entry" classes.

This avoids crashes caused by converting src/glsl to automake.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-and-tested-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/glsl/opt_dead_code.cpp

@@ -50,7 +50,7 @@ do_dead_code(exec_list *instructions, bool uniform_locations_assigned)
    v.run(instructions);
 
    foreach_iter(exec_list_iterator, iter, v.variable_list) {
-      variable_entry *entry = (variable_entry *)iter.get();
+      ir_variable_refcount_entry *entry = (ir_variable_refcount_entry *)iter.get();
 
       /* Since each assignment is a reference, the refereneced count must be
        * greater than or equal to the assignment count.  If they are equal,