validate_failures.py (GetManifestPath): Simplify

... and don't require a valid build directory when no data from it
is necessary.

Change-Id: I1883bcba58f08a079cee417abaca37e3f36cff1e
diff --git a/contrib/testsuite-management/validate_failures.py b/contrib/testsuite-management/validate_failures.py
index da801a0..8dbf8f0 100755
--- a/contrib/testsuite-management/validate_failures.py
+++ b/contrib/testsuite-management/validate_failures.py
@@ -440,7 +440,7 @@
   return actual_vs_manifest, manifest_vs_actual
 
 
-def GetManifestPath(srcdir, target, user_provided_must_exist):
+def GetManifestPath(user_provided_must_exist):
   """Return the full path to the manifest file."""
   manifest_path = _OPTIONS.manifest
   if manifest_path:
@@ -448,6 +448,7 @@
       Error('Manifest does not exist: %s' % manifest_path)
     return manifest_path
   else:
+    (srcdir, target) = GetBuildData()
     if not srcdir:
       Error('Could not determine the location of GCC\'s source tree. '
             'The Makefile does not contain a definition for "srcdir".')
@@ -513,8 +514,7 @@
 
 
 def CheckExpectedResults():
-  srcdir, target = GetBuildData()
-  manifest_path = GetManifestPath(srcdir, target, True)
+  manifest_path = GetManifestPath(True)
   print('Manifest:         %s' % manifest_path)
   manifest = GetManifest(manifest_path)
   sum_files = GetSumFiles(_OPTIONS.results, _OPTIONS.build_dir)
@@ -528,8 +528,7 @@
 
 
 def ProduceManifest():
-  (srcdir, target) = GetBuildData()
-  manifest_path = GetManifestPath(srcdir, target, False)
+  manifest_path = GetManifestPath(False)
   print('Manifest:         %s' % manifest_path)
   if os.path.exists(manifest_path) and not _OPTIONS.force:
     Error('Manifest file %s already exists.\nUse --force to overwrite.' %
@@ -546,15 +545,13 @@
 
 
 def CompareBuilds():
-  (srcdir, target) = GetBuildData()
-
   sum_files = GetSumFiles(_OPTIONS.results, _OPTIONS.build_dir)
   actual = GetResults(sum_files)
 
   clean = ResultSet()
 
   if _OPTIONS.manifest:
-    manifest_path = GetManifestPath(srcdir, target, True)
+    manifest_path = GetManifestPath(True)
     print('Manifest:         %s' % manifest_path)
     clean = GetManifest(manifest_path)