Mark libmetricslogger vendor_available.

libmetricslogger is a library which 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

Merged-In: Id50e1bb8a7a4fecfde35a63439ac28b1be883e21
Change-Id: If4bb63d3769317bc7cfc0f2f326e8bdd7b565ebe
(cherry picked from commit 7f96d493705dd00757597018e6befa20b15bfc8b)
diff --git a/libmetricslogger/Android.bp b/libmetricslogger/Android.bp
index da8afe1..79d6c3f 100644
--- a/libmetricslogger/Android.bp
+++ b/libmetricslogger/Android.bp
@@ -30,6 +30,7 @@
 // -----------------------------------------------------------------------------
 cc_library_shared {
     name: "libmetricslogger",
+    vendor_available: true,
     srcs: metricslogger_lib_src_files,
     defaults: ["metricslogger_defaults"],
 }