Fix toybox_vendor dependencies on libselinux_vendor.

Fix toybox_vendor dependencies on libselinux_vendor.

toybox_vendor now links to other libraries as shared libraries.
This allows toybox_vendor to use the "vendor" version of these libraries
(in particular, liblog and libselinx_vendor).

Test: mma -j
Test: m -j, flash, boots
Test: `adb shell /vendor/bin/restorecon /dev/null` shows error message
Test: `adb shell /vendor/bin/getprop -Z' shows error message
Test: mma -j BOARD_VNDK_VERSION=current

Bug: 62886649

(revert of commit 4ab405afe2668a5ca25be411df2d05a5e0995478)
(resubmit of commit e06cffe06993e0ade6f7836becb26e7f076c8a68)

Change-Id: I0812b58eb3d769d1a73e64009481075c09da2450
Merged-In: If01094b71ef7e99b5756b851132de643660a1e2c