Use GTEST_SKIP() to skip tests

GTEST_SKIP() is better than manually logging and return,
the former is able to print hint messages and the skipped
tests in summaries, for example:

$ bin/fs_manager-test --gtest_filter=*TestAddRemoveDataDirs*
...
[ RUN      ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirs/0
...
Skipping test, file block manager not supported
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirs/0 (10 ms)
...
[==========] 12 tests from 1 test suite ran. (6407 ms total)
[  PASSED  ] 6 tests.
[  SKIPPED ] 6 tests, listed below:
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirs/0
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirs/1
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirs/2
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirsFuzz/0
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirsFuzz/1
[  SKIPPED ] BlockManagerTypes/FsManagerTestBase.TestAddRemoveDataDirsFuzz/2

Change-Id: Id3c39255e97cfc67a8cb8d01f8aefa74d570e786
Reviewed-on: http://gerrit.cloudera.org:8080/20875
Tested-by: Yingchun Lai <laiyingchun@apache.org>
Reviewed-by: Alexey Serbin <alexey@apache.org>
16 files changed