Mark libselinux as double_loadable

libselinux is a VNDK lib and also used by LLNDK(libmediandk) which means
this lib can be double-loaded.
(deps: libmediandk -> libmedia_jni -> libandroid_runtime -> libselinux)

Bug: 121280180
Test: m -j
Change-Id: Ie7a583088a97cf68f7ae547b6d63f970efa559e8
1 file changed