glsl: Hook up loop_variable_state destructor to plug a memory leak.

While ~loop_state() is already freeing the loop_variable_state objects
via ralloc_free(this->mem_ctx), the ~loop_variable_state() destructor
was never getting called, so the hash table inside loop_variable_state
was never getting destroyed.

Fixes a memory leak in any shader with loops.

NOTE: This is a candidate for stable release branches.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/loop_analysis.h

@@ -140,6 +140,23 @@ public:
    {
       hash_table_dtor(this->var_hash);
    }
+
+   static void* operator new(size_t size, void *ctx)
+   {
+      void *lvs = ralloc_size(ctx, size);
+      assert(lvs != NULL);
+
+      ralloc_set_destructor(lvs, (void (*)(void*)) destructor);
+
+      return lvs;
+   }
+
+private:
+   static void
+   destructor(loop_variable_state *lvs)
+   {
+      lvs->~loop_variable_state();
+   }
 };