Upgrade rust/crates/memoffset to 0.6.3

Test: make
Change-Id: I9277d354259896b50e617b7822ffeeedcaff4928

Android.bp

diff --git a/Android.bp b/Android.bp
index 5b98902..ae913ce 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,5 @@
 // This file is generated by cargo2android.py --run --device --tests --dependencies --patch=patches/Android.bp.patch.
+// Do not modify this file as changes will be overridden on upgrade.
 
 package {
     default_applicable_licenses: ["external_rust_crates_memoffset_license"],
@@ -59,6 +60,9 @@
 rust_test_host {
     name: "memoffset_host_test_src_lib",
     defaults: ["memoffset_defaults"],
+    test_options: {
+        unit_test: true,
+    },
 }
 
 rust_test {