Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/rtc_base/meson.build

@@ -0,0 +1,64 @@
+base_sources = [
+  'checks.cc',
+  'event.cc',
+  'event_tracer.cc',
+  'experiments/field_trial_parser.cc',
+  'logging.cc',
+  'memory/aligned_malloc.cc',
+  'platform_thread.cc',
+  'platform_thread_types.cc',
+  'race_checker.cc',
+  'string_encode.cc',
+  'string_to_number.cc',
+  'string_utils.cc',
+  'strings/string_builder.cc',
+  'synchronization/mutex.cc',
+  'synchronization/rw_lock_wrapper.cc',
+  'synchronization/yield.cc',
+  'synchronization/yield_policy.cc',
+  'system/file_wrapper.cc',
+  'time_utils.cc',
+  'zero_memory.cc',
+]
+
+base_headers = [
+  [ '', 'arraysize.h' ],
+  [ '', 'checks.h' ],
+  [ '', 'constructor_magic.h' ],
+  [ '', 'deprecation.h' ],
+  [ '', 'ref_count.h' ],
+  [ '', 'type_traits.h' ],
+  [ 'numerics', 'safe_compare.h' ],
+  [ 'system', 'file_wrapper.h' ],
+  [ 'system', 'inline.h' ],
+  [ 'system', 'rtc_export.h' ],
+]
+
+if have_posix
+  base_sources += [
+    'synchronization/rw_lock_posix.cc',
+  ]
+elif have_win
+  base_sources += [
+    'synchronization/rw_lock_win.cc',
+  ]
+endif
+
+foreach h : base_headers
+  install_headers(
+    join_paths(h[0], h[1]),
+    subdir: join_paths('webrtc_audio_processing', 'rtc_base', h[0])
+  )
+endforeach
+
+libbase = static_library('libbase',
+    base_sources,
+    dependencies: common_deps,
+    include_directories: webrtc_inc,
+    cpp_args : common_cxxflags
+)
+
+base_dep = declare_dependency(
+    link_with: libbase
+)
+