[test] Skip a test when using an out-of-tree debugserver

The test "test_fp_special_purpose_register_read" in TestRegisters.py
fails on Darwin machines configured to use an out-of-tree debugserver.

The error message is: 'register read ftag' returns expected result, got
'ftag = 0x80'. This indicates that the debugserver in use is too old.

This commit introduces a decorator which can be used to skip tests which
rely on having a just-built debugserver. This resolves the issue:

$ ./bin/llvm-dotest -p TestRegisters.py -v
  1 out of 617 test suites processed - TestRegisters.py
  Test Methods:          7
  Success:               6
  Skip:                  1
...

llvm-svn: 327052

1 files changed, 5 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/dotest_args.py b/lldb/packages/Python/lldbsuite/test/dotest_args.py
index c6e4a4bd170..1f3eca39d06 100644
--- a/lldb/packages/Python/lldbsuite/test/dotest_args.py
+++ b/lldb/packages/Python/lldbsuite/test/dotest_args.py
@@ -127,6 +127,11 @@ def create_parser():
         metavar='server-path',
         help='The path to the debug server executable to use')
     group.add_argument(
+        '--out-of-tree-debugserver',
+        dest='out_of_tree_debugserver',
+        action='store_true',
+        help='A flag to indicate an out-of-tree debug server is being used')
+    group.add_argument(
         '-s',
         metavar='name',
         help='Specify the name of the dir created to store the session files of tests with errored or failed status. If not specified, the test driver uses the timestamp as the session dir name')