Export more symbols for init

Following symbols from libselinux are used by init. They need to be
exposed in order for the init to dynamically link to libselinux.

Note that this does not affect symbols visibility to vendor, which is
controlled by other map file, exported_vendor.map.

Bug: 63673171
Test: m -j
Test: adb reboot recovery
Change-Id: Ic149801b60fc739ab99f29711a522d460001a293
1 file changed