Remove unused ConditionVariableWrapper on POSIX platforms

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.
 
 import("//build/config/android/config.gni")
 import("../build/webrtc.gni")
@@ skipping 32 matching lines @@
     "include/utf_util_win.h",
     "source/aligned_malloc.cc",
     "source/atomic32_mac.cc",
     "source/atomic32_win.cc",
     "source/clock.cc",
     "source/condition_variable.cc",
     "source/condition_variable_event_win.cc",
     "source/condition_variable_event_win.h",
     "source/condition_variable_native_win.cc",
     "source/condition_variable_native_win.h",
-    "source/condition_variable_posix.cc",
-    "source/condition_variable_posix.h",
     "source/cpu_features.cc",
     "source/cpu_info.cc",
     "source/critical_section.cc",
     "source/data_log_c.cc",
     "source/event.cc",
     "source/event_timer_posix.cc",
     "source/event_timer_posix.h",
     "source/event_timer_win.cc",
     "source/event_timer_win.h",
     "source/file_impl.cc",
@@ skipping 130 matching lines @@
       "source/cpu_features_android.c",
     ]
 
     configs += [ "..:common_config" ]
     public_configs = [ "..:common_inherited_config" ]
     deps = [
       "//third_party/android_tools:cpu_features",
     ]
   }
 }