Add exp.h path in the micro Makefile
diff --git a/tensorflow/lite/micro/tools/make/Makefile b/tensorflow/lite/micro/tools/make/Makefile
index 3b10de0..4720670 100644
--- a/tensorflow/lite/micro/tools/make/Makefile
+++ b/tensorflow/lite/micro/tools/make/Makefile
@@ -400,6 +400,7 @@
 tensorflow/lite/kernels/internal/reference/depthwiseconv_float.h \
 tensorflow/lite/kernels/internal/reference/depthwiseconv_uint8.h \
 tensorflow/lite/kernels/internal/reference/dequantize.h \
+tensorflow/lite/kernels/internal/reference/exp.h \
 tensorflow/lite/kernels/internal/reference/floor.h \
 tensorflow/lite/kernels/internal/reference/fully_connected.h \
 tensorflow/lite/kernels/internal/reference/hard_swish.h \