[lldb] Use realpath to avoid issues with symlinks in source paths

[aadsm]

Summary

I was not able to sucessfully run TestDSYMSourcePathRemapping.py because the source mapping was using /tmp/ but the debugger was checking /private/tmp (which is a symlink to tmp). Maybe the debugger should realpath on it? Not sure but by making sure our tests always use the real path it avoids these kind of issues.

[clayborg]

Might be a better idea to realpath this once in the setup code instead of calling realpath thousands and thousands of times? Maybe we just santize "LLDB_TEST" and "LLDB_BUILD" one time with top level code like:

os.environ["LLDB_TEST"] = os.path.realpath(os.environ["LLDB_TEST"])
os.environ["LLDB_BUILD"] = os.path.realpath(os.environ["LLDB_BUILD"])

[aadsm]

Solve this at the failing test level. We can't be sure of the filename will end up in the debug info so we just add both keys to the mapping.

lldb/packages/Python/lldbsuite/test/lldbtest.py

def setPlatformWorkingDir(self):
             # list of files we have to remove during test runs.
             shell_cmd = lldb.SBPlatformShellCommand(
                 "rm %s/*" % remote_test_dir)
             lldb.remote_platform.Run(shell_cmd)
         self.addTearDownHook(clean_working_directory)
 
     def getSourceDir(self):
         """Return the full path to the current test."""
-        return os.path.join(os.environ["LLDB_TEST"], self.mydir)
+        return os.path.realpath(os.path.join(os.environ["LLDB_TEST"], self.mydir))
 
     def getBuildDirBasename(self):
         return self.__class__.__module__ + "." + self.testMethodName
 
     def getBuildDir(self):
         """Return the full path to the current test."""
-        return os.path.join(os.environ["LLDB_BUILD"], self.mydir,
-                            self.getBuildDirBasename())
+        return os.path.realpath(os.path.join(os.environ["LLDB_BUILD"], self.mydir,
+                            self.getBuildDirBasename()))
 
 
     def makeBuildDir(self):
         """Create the test-specific working directory, deleting any previous
         contents."""
         # See also dotest.py which sets up ${LLDB_BUILD}.
         bdir = self.getBuildDir()
         if os.path.isdir(bdir):