Mark libsysutils vendor_available.

libsysutils 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: I3ef1d09c7e836549eb13ce68ac7cdcd5923bde0f
diff --git a/libsysutils/Android.bp b/libsysutils/Android.bp
index 296bd26..550ef42 100644
--- a/libsysutils/Android.bp
+++ b/libsysutils/Android.bp
@@ -1,5 +1,7 @@
 cc_library_shared {
     name: "libsysutils",
+    vendor_available: true,
+
     srcs: [
         "src/SocketListener.cpp",
         "src/FrameworkListener.cpp",