Build an NDK variant of the WUFFS build target

This enables other NDK compliant libraries and tests
within Android to statically link the WUFFS build target.

Bug: 213467181
Change-Id: I06e12d1a2112b859842aed588ca90511af9c7ddd
Test: build only change
diff --git a/Android.bp b/Android.bp
index a69437b..c928405 100644
--- a/Android.bp
+++ b/Android.bp
@@ -28,6 +28,7 @@
     srcs: [
         "release/c/wuffs-v0.3.c",
     ],
+    sdk_version: "minimum",
     host_supported: true,
     target: {
       windows: {