Fix for default library path "/vendor/lib"

Android N restrict which libraries C/C++ code
can link against at runtime.

If device has a vendor partition
then /system/vendor symlink to /vendor.
Otherwise /vendor symlink to /system/vendor.

But is_system_library() is only checking /vendor/lib.
It will return false for /system/vendor/lib path.
It is need to add a real path to default library path.

Similarily, default ld library path is already checking.
parse_LD_LIBRARY_PATH()->parse_path()->resolve_paths()

Test: build bionic and run bionic-unit-tests
Bug: http://b/31919547


Change-Id: Ie6777e2b02729948ce77a94de32343d40358bf2c
Signed-off-by: Hyangseok Chae <neo.chae@lge.com>
(cherry picked from commit 2589f9de)