Store absolute path for lldb executable in dotest.py

[fjricci]

Summary

lldb-server tests are currently being skipped on the
check-lldb target. This is because we get the path of
lldb-server by modifying the path to the lldb executable.
However, by this point, we've changed directories, and a
relative path to the build/bin directory will no longer point
to the location of lldb-server.

Storing an absolute path solves this issue.

[labath]

Not sure what is the difference, but my check-lldb target has already the full path in it. Sounds like a good idea nonetheless.

[tfiala]

Didn't get to it in time, but yes this looks fine.

packages/Python/lldbsuite/test/dotest.py

def parseOptionsAndInitTestdirs():
 
     if args.l:
         configuration.skip_long_running_test = False
 
     if args.framework:
         configuration.lldbFrameworkPath = args.framework
 
     if args.executable:
-        lldbtest_config.lldbExec = args.executable
+        lldbtest_config.lldbExec = os.path.realpath(args.executable)
 
     if args.p:
         if args.p.startswith('-'):
             usage(parser)
         configuration.regexp = args.p
 
     if args.q:
         configuration.parsable = True