glsl: Add linker support for explicit attribute locations
diff --git a/src/glsl/ir_variable.cpp b/src/glsl/ir_variable.cpp
index 1eff740..ddc3bb0 100644
--- a/src/glsl/ir_variable.cpp
+++ b/src/glsl/ir_variable.cpp
@@ -52,6 +52,7 @@
    }
 
    var->location = slot;
+   var->explicit_location = (slot >= 0);
 
    /* Once the variable is created an initialized, add it to the symbol table
     * and add the declaration to the IR stream.