glsl2: Remove the const disease from function signature's callee.
diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 467722c..aaf1e57 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -64,8 +64,7 @@
 {
    void *ctx = state;
 
-   const ir_function_signature *sig =
-      f->matching_signature(actual_parameters);
+   ir_function_signature *sig = f->matching_signature(actual_parameters);
 
    /* The instructions param will be used when the FINISHMEs below are done */
    (void) instructions;