Delete stl_util.h. Unused since cl https://codereview.webrtc.org/2447103002

webrtc/system_wrappers/BUILD.gn

 # Copyright (c) 2014 The WebRTC 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 in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 if (is_android) {
   import("//build/config/android/config.gni")
@@ skipping 14 matching lines @@
     "include/field_trial.h",
     "include/file_wrapper.h",
     "include/fix_interlocked_exchange_pointer_win.h",
     "include/logging.h",
     "include/metrics.h",
     "include/ntp_time.h",
     "include/rtp_to_ntp.h",
     "include/rw_lock_wrapper.h",
     "include/sleep.h",
     "include/static_instance.h",
-    "include/stl_util.h",
     "include/stringize_macros.h",
     "include/timestamp_extrapolator.h",
     "include/trace.h",
     "include/utf_util_win.h",
     "source/aligned_malloc.cc",
     "source/atomic32_win.cc",
     "source/clock.cc",
     "source/condition_variable_event_win.cc",
     "source/condition_variable_event_win.h",
     "source/cpu_features.cc",
@@ skipping 128 matching lines @@
       "source/aligned_malloc_unittest.cc",
       "source/clock_unittest.cc",
       "source/condition_variable_unittest.cc",
       "source/critical_section_unittest.cc",
       "source/event_timer_posix_unittest.cc",
       "source/logging_unittest.cc",
       "source/metrics_default_unittest.cc",
       "source/metrics_unittest.cc",
       "source/ntp_time_unittest.cc",
       "source/rtp_to_ntp_unittest.cc",
-      "source/stl_util_unittest.cc",
       "source/stringize_macros_unittest.cc",
     ]
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
     if (!build_with_chromium && is_clang) {
       # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
       suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
     }
 
     deps = [
       ":metrics_default",
       ":system_wrappers",
       "../test:test_main",
       "//testing/gtest",
     ]
 
     if (is_android) {
       deps += [ "//testing/android/native_test:native_test_support" ]
 
       shard_timeout = 900
     }
   }
 }