Mark libs as double_loadable

libs(libasyncio libmemtrack libprocinfo libusbhost) have
vendor variants and they are also used by LLNDK(libmediandk)
which means these libs can be double-loaded.

deps:
- libmediandk -> libmedia_jni -> libmtp -> libasyncio
- libmediandk -> libmedia_jni -> libandroid_runtime -> libmemtrack
- libmediandk -> libmedia_jni -> libandroid_runtime -> libdebuggerd_client -> libprocinfo
- libmediandk -> libmedia_jni -> libmtp -> libusbhost

Bug: 121280180
Test: m -j
Change-Id: I2c2b5d67cf47b85a2aa8c08f85c7e1a84490cf4e
diff --git a/libmemtrack/Android.bp b/libmemtrack/Android.bp
index 4e4554a..320b851 100644
--- a/libmemtrack/Android.bp
+++ b/libmemtrack/Android.bp
@@ -6,6 +6,7 @@
     vndk: {
         enabled: true,
     },
+    double_loadable: true,
     srcs: ["memtrack.cpp"],
     export_include_dirs: ["include"],
     local_include_dirs: ["include"],