mesa: move STATE_LENGTH to shader_enums.h and use it everywhere

Reviewed-by: Brian Paul <brianp@vmware.com>

src/compiler/shader_enums.h

@@ -48,6 +48,12 @@ typedef enum
    MESA_SHADER_COMPUTE = 5,
 } gl_shader_stage;
 
+/**
+ * Number of STATE_* values we need to address any GL state.
+ * Used to dimension arrays.
+ */
+#define STATE_LENGTH 5
+
 typedef short gl_state_index16; /* see enum gl_state_index */
 
 const char *gl_shader_stage_name(gl_shader_stage stage);