Fix the 6KB binary size increase.
Fix the 6KB binary size increase.

https://github.com/tensorflow/tensorflow/commit/9ee7896d229278f582a3a381c6d22ec0559d9765
added a function that was unused for the TFLM build yet still
contributed to a 6KB binary size increase.

This change moves that function inside #ifndef TF_LITE_STATIC_MEMORY and
so avoids the size increase.

Manually tested with the following commands:
```
make -f tensorflow/lite/micro/tools/make/Makefile TARGET=xtensa OPTIMIZED_KERNEL_DIR=xtensa TARGET_ARCH=fusion_f1 XTENSA_CORE=F1_190305_swupgrade keyword_benchmark -j8 BUILD_TYPE=release
xt-size tensorflow/lite/micro/tools/make/gen/xtensa_fusion_f1_release/bin/keyword_benchmark
```

Before this change:
```
   text	   data	    bss	    dec
  67192	  44512	  24968	 136672
```

After this change:
```
   text	   data	    bss	    dec
  62184	  40180	  24872	 127236
```

Fixes http://b/178731766

petewarden/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow,annarev/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow,karllessard/tensorflow,annarev/tensorflow,sarvex/tensorflow,Intel-tensorflow/tensorflow,petewarden/tensorflow,paolodedios/tensorflow,annarev/tensorflow,Intel-tensorflow/tensorflow,tensorflow/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,frreiss/tensorflow-fred,Intel-Corporation/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,karllessard/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,yongtang/tensorflow,petewarden/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,yongtang/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_tf_optimizer,Intel-tensorflow/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,frreiss/tensorflow-fred,frreiss/tensorflow-fred,frreiss/tensorflow-fred,frreiss/tensorflow-fred,tensorflow/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,petewarden/tensorflow,Intel-tensorflow/tensorflow,yongtang/tensorflow,karllessard/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_saved_model,petewarden/tensorflow,petewarden/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,petewarden/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-pywrap_saved_model,petewarden/tensorflow,tensorflow/tensorflow,yongtang/tensorflow,petewarden/tensorflow,sarvex/tensorflow,paolodedios/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,Intel-tensorflow/tensorflow,annarev/tensorflow,karllessard/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,Intel-Corporation/tensorflow,sarvex/tensorflow,tensorflow/tensorflow,paolodedios/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow-pywrap_tf_optimizer,paolodedios/tensorflow,gautam1858/tensorflow,annarev/tensorflow,Intel-Corporation/tensorflow,gautam1858/tensorflow,Intel-tensorflow/tensorflow,Intel-tensorflow/tensorflow,frreiss/tensorflow-fred,paolodedios/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,Intel-Corporation/tensorflow,paolodedios/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,paolodedios/tensorflow,sarvex/tensorflow,paolodedios/tensorflow,tensorflow/tensorflow-pywrap_saved_model,karllessard/tensorflow,Intel-Corporation/tensorflow,gautam1858/tensorflow,sarvex/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow,tensorflow/tensorflow,Intel-tensorflow/tensorflow,frreiss/tensorflow-fred,annarev/tensorflow,frreiss/tensorflow-fred,frreiss/tensorflow-fred,annarev/tensorflow,frreiss/tensorflow-fred,Intel-Corporation/tensorflow,annarev/tensorflow,tensorflow/tensorflow,gautam1858/tensorflow,yongtang/tensorflow,petewarden/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-pywrap_saved_model,karllessard/tensorflow,Intel-tensorflow/tensorflow,annarev/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,Intel-tensorflow/tensorflow,sarvex/tensorflow,Intel-Corporation/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,frreiss/tensorflow-fred,petewarden/tensorflow,tensorflow/tensorflow-pywrap_saved_model,yongtang/tensorflow,yongtang/tensorflow,annarev/tensorflow,tensorflow/tensorflow-pywrap_saved_model,Intel-tensorflow/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,paolodedios/tensorflow,annarev/tensorflow,sarvex/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,karllessard/tensorflow,paolodedios/tensorflow,frreiss/tensorflow-fred,tensorflow/tensorflow-experimental_link_static_libraries_once,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-experimental_link_static_libraries_once,petewarden/tensorflow,sarvex/tensorflow,yongtang/tensorflow,Intel-Corporation/tensorflow