encoder_utils: Fix implicit declaration

Example warning:

```c
av1/encoder/encoder_utils.c: In function 'av1_determine_sc_tools_with_encoding':
av1/encoder/encoder_utils.c:976:11: warning: implicit declaration of function 'av1_get_vmaf_base_qindex'; did you mean 'av1_get_txb_size_index'? [-Wimplicit-function-declaration]
  976 |           av1_get_vmaf_base_qindex(cpi, q_for_screen_content_quick_run),
      |           ^~~~~~~~~~~~~~~~~~~~~~~~
      |           av1_get_txb_size_index
```

Change-Id: Ida5b64aecb1435f4d755e7006952bb691498b43d
diff --git a/av1/encoder/encoder_utils.c b/av1/encoder/encoder_utils.c
index 9baea60..7209054 100644
--- a/av1/encoder/encoder_utils.c
+++ b/av1/encoder/encoder_utils.c
@@ -25,6 +25,10 @@
 #include "av1/encoder/superres_scale.h"
 #include "av1/encoder/var_based_part.h"
 
+#if CONFIG_TUNE_VMAF
+#include "av1/encoder/tune_vmaf.h"
+#endif
+
 #define MIN_BOOST_COMBINE_FACTOR 4.0
 #define MAX_BOOST_COMBINE_FACTOR 12.0