[tools] Include full benchmark measurement name in error reporting

tools/run_perf.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 Performance runner for d8.
 
 Call e.g. with tools/run-perf.py --arch ia32 some_suite.json
 
@@ skipping 161 matching lines @@
     return str(self.ToDict())
 
 
 class Measurement(object):
   """Represents a series of results of one trace.
 
   The results are from repetitive runs of the same executable. They are
   gathered by repeated calls to ConsumeOutput.
   """
   def __init__(self, graphs, units, results_regexp, stddev_regexp):
-    self.name = graphs[-1]
+    self.name = '/'.join(graphs)
     self.graphs = graphs
     self.units = units
     self.results_regexp = results_regexp
     self.stddev_regexp = stddev_regexp
     self.results = []
     self.errors = []
     self.stddev = ""
 
   def ConsumeOutput(self, stdout):
     try:
@@ skipping 879 matching lines @@
 
   if options.json_test_results_no_patch:
     results_no_patch.WriteToFile(options.json_test_results_no_patch)
   else:  # pragma: no cover
     print results_no_patch
 
   return min(1, len(results.errors))
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(Main(sys.argv[1:]))