Optimized TFLM Reshape for kelvin

- Add a TFLM patch which contains a Kelvin-specific kernel for reshape,
  which is implemented using an optimized memcpy.
- Add the `opt` library, which at the moment simply contains the
  optimized memcpy routine.
- Wrap up the `reshape_test` from TFLM into a buildable target.

Change-Id: I77f54fdc635838e8d272e47a8ff8654e7f23373e
diff --git a/tflm/opt/BUILD b/tflm/opt/BUILD
new file mode 100644
index 0000000..abf99e6
--- /dev/null
+++ b/tflm/opt/BUILD
@@ -0,0 +1,16 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "opt",
+    srcs = [
+        "memcpy.cc",
+    ],
+    hdrs = [
+        "opt.h",
+    ],
+    deps = [
+        "//crt:crt_header",
+    ],
+    alwayslink = True,
+    target_compatible_with = ["@kelvin_sw//platforms/cpu:kelvin"],
+)