Mark liblz4 vendor_available.

liblz4 belongs to vndk-cap. Mark it vendor_available to enable vndk
abi stability checks on it.

Details: https://android-review.googlesource.com/368372

Test: mm -j64

Bug: 38244611

Change-Id: I30b6908b1e29d157f7fd958805a697489bd2e242
diff --git a/lib/Android.bp b/lib/Android.bp
index 19d02a3..0599a7e 100644
--- a/lib/Android.bp
+++ b/lib/Android.bp
@@ -2,6 +2,7 @@
 
 cc_library {
     name: "liblz4",
+    vendor_available: true,
     host_supported: true,
     srcs: [
         "lz4.c",