Add unit tests for sun.nio.fs.UnixSecureDirectoryStream

Also, some constants(O_NOFOLLOW) in UnixConstants were not correct for
arm64 and arm. They were generated on an x86 system. Therefore, instead of
maintaining a separate set of UnixConstants, the values are now taken
from android.system.OsConstants. S_IAMB are access mode bits, therefore,
calculated by taking OR of all the read, write and execute permissions
bits for owner, group and other. AT_SYMLINK_NOFOLLOW is used by fstatat
when a symbolic link is passed. With AT_SYMLINK_NOLLOW, it doesn't
dereference and instead return information about the link, and with it,
returns the information about the target. There is no suitable alternative
for the flag in android.system.OsConstant, therefore, left untouched.
With AT_REMOVEDIR, unlinkat works equivalent to rmdir. Again there is no
suitable alternative for the flag in android.system.OsConstant,
therefore, left unchanged.

Bug: 29031119
Bug: 32203242
Test: cts-tradefed run cts -m CtsLibcoreTestCases -t \
        libcore.java.nio.file.DefaultSecureDirectoryStreamTest
Change-Id: Ie7f8ce46d19e3549cc69dba4cb2a9717df1cca18

0 files changed, 0 insertions, 0 deletions