adds dep needed for xtensa fft (#2409)

BUG=[323060097](https://b.corp.google.com/issues/323060097)
diff --git a/tensorflow/lite/micro/tools/make/ext_libs/xtensa.inc b/tensorflow/lite/micro/tools/make/ext_libs/xtensa.inc
index b6db417..bec226a 100644
--- a/tensorflow/lite/micro/tools/make/ext_libs/xtensa.inc
+++ b/tensorflow/lite/micro/tools/make/ext_libs/xtensa.inc
@@ -125,7 +125,8 @@
     $(shell find $(NDSPLIB_PATH)/library/fft/fft -name "*.c") \
     $(shell find $(NDSPLIB_PATH)/library/fft/fft_ie -name "*.c") \
     $(shell find $(NDSPLIB_PATH)/library/fft/fft_ief -name "*.c") \
-    $(shell find $(NDSPLIB_PATH)/library/twiddles -name "*.c")
+    $(shell find $(NDSPLIB_PATH)/library/twiddles -name "*.c") \
+    $(shell find $(NDSPLIB_PATH)/library/vector -name "*.c")
 
   EXCLUDED_NNLIB_SRCS = \
     $(NNLIB_PATH)/algo/layers/cnn/src/xa_nn_cnn_api.c \