[debuginfo-tests] commands.getoutput -> subprocess.check_output

We should also make Darwin Python3 happy after r346059
The output has an extra newline but it is fine in this particular case.

llvm-svn: 346066
GitOrigin-RevId: 93deae23d1d9202168444f90756daf801feb1537
diff --git a/lit.cfg.py b/lit.cfg.py
index ac922c4..a806c12 100644
--- a/lit.cfg.py
+++ b/lit.cfg.py
@@ -63,8 +63,8 @@
 lit.util.usePlatformSdkOnDarwin(config, lit_config)
 
 if platform.system() == 'Darwin':
-    import commands
-    xcode_lldb_vers = commands.getoutput("xcrun lldb --version")
+    import subprocess
+    xcode_lldb_vers = subprocess.check_output(['xcrun', 'lldb', '--version'])
     match = re.search('lldb-(\d+)', xcode_lldb_vers)
     if match:
         apple_lldb_vers = int(match.group(1))