libvpx: Pull from upstream

source/libvpx/vp8/common/generic/systemdependent.c

 /*
  *  Copyright (c) 2010 The WebM 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.
  */
 
@@ skipping 64 matching lines @@
         }
     }
 #else
     /* other platforms */
 #endif
 
     return core_count > 0 ? core_count : 1;
 }
 #endif
 
+void vp8_clear_system_state_c() {};
 
 void vp8_machine_specific_config(VP8_COMMON *ctx)
 {
 #if CONFIG_MULTITHREAD
     ctx->processor_core_count = get_cpu_count();
 #endif /* CONFIG_MULTITHREAD */
 
 #if ARCH_ARM
     ctx->cpu_caps = arm_cpu_caps();
 #elif ARCH_X86 || ARCH_X86_64
     ctx->cpu_caps = x86_simd_caps();
 #endif
 }