Add a bunch of missing string.h / cstring includes in //media.

There is a lot of code in the tree that uses various functions defined
in string.h (memcpy, strlen, strnlen, memmove, etc), but never includes
the necessary header file. At least on Linux it still works fine with
bundled sysroots, or when using system headers based on glibc 2.29.
Starting with glibc 2.30 this is no longer the case. There are quite a
few files which fail to compile because the compiler can't see the
definitions of some functions normally defined in string.h.

Bug: 1074286
Change-Id: I24541cea1c1b43ec1d7bccdce1c504aebdf33f2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2164607
Commit-Queue: Piotr Tworek <ptworek@vewd.com>
Reviewed-by: Ted Meyer <tmathmeyer@chromium.org>
Reviewed-by: Tommi <tommi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762754}

media/base/audio_bus.cc

@@ -7,6 +7,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <cstring>
 #include <limits>
 #include <utility>
 

media/base/audio_fifo.cc

@@ -4,6 +4,8 @@
 
 #include "media/base/audio_fifo.h"
 
+#include <cstring>
+
 #include "base/check_op.h"
 
 namespace media {

media/base/bit_reader_core.cc

@@ -5,6 +5,7 @@
 #include "media/base/bit_reader_core.h"
 
 #include <stdint.h>
+#include <cstring>
 
 #include "base/sys_byteorder.h"
 

media/base/byte_queue.cc

@@ -5,6 +5,7 @@
 #include "media/base/byte_queue.h"
 
 #include <algorithm>
+#include <cstring>
 
 #include "base/check_op.h"
 #include "base/numerics/checked_math.h"

media/base/channel_mixer.cc

@@ -5,6 +5,7 @@
 #include "media/base/channel_mixer.h"
 
 #include <stddef.h>
+#include <string.h>
 
 #include "base/check_op.h"
 #include "media/base/audio_bus.h"

media/base/container_names.cc

@@ -5,6 +5,7 @@
 #include "media/base/container_names.h"
 
 #include <stddef.h>
+#include <string.h>
 
 #include <cctype>
 #include <limits>

media/base/video_bitrate_allocation.cc

@@ -4,6 +4,7 @@
 
 #include "video_bitrate_allocation.h"
 
+#include <cstring>
 #include <limits>
 #include <numeric>
 

media/filters/ivf_parser.cc

@@ -4,6 +4,8 @@
 
 #include "media/filters/ivf_parser.h"
 
+#include <cstring>
+
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/sys_byteorder.h"

media/filters/wsola_internals.cc

@@ -6,6 +6,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <cstring>
 #include <limits>
 #include <memory>
 

media/formats/webm/tracks_builder.cc

@@ -4,6 +4,8 @@
 
 #include "media/formats/webm/tracks_builder.h"
 
+#include <cstring>
+
 #include "base/check_op.h"
 #include "media/formats/webm/webm_constants.h"
 

media/formats/webm/webm_parser.cc

@@ -13,6 +13,7 @@
 
 #include <stddef.h>
 
+#include <cstring>
 #include <iomanip>
 #include <limits>
 

media/learning/common/value.cc

@@ -4,6 +4,8 @@
 
 #include "media/learning/common/value.h"
 
+#include <cstring>
+
 #include "base/hash/hash.h"
 
 namespace media {

media/parsers/jpeg_parser.cc

@@ -4,6 +4,8 @@
 
 #include "media/parsers/jpeg_parser.h"
 
+#include <cstring>
+
 #include "base/big_endian.h"
 #include "base/logging.h"
 #include "base/stl_util.h"

media/parsers/vp8_parser.cc

@@ -7,6 +7,8 @@
 
 #include "media/parsers/vp8_parser.h"
 
+#include <cstring>
+
 #include "base/logging.h"
 
 namespace media {