Add a bunch of missing string.h includes.

There are a few files in the tree which use various functions defined
in string.h (memcpy, strlen, strnlen, memmove, etc), but never include
the necessary header file. After I've recently updated one of my systems
to a newer glibc version (2.30) this code failed to build. Adding the
missing includes fixes the problem.

The undeclared functions for each file are:
* simple_address_range_bag.h - memcpy
* http_multipart_builder.cc - strlen
* minidump_context_converter.cc - memcpy
* ptrace_client.cc - strlen
* http_transport_socket.cc - strncpy, strlen, memcpy
* process_memory.cc - memchr
* log_output_stream.cc - strlen

Change-Id: I3108c36b8a6927ac11f6839606cb495926fa9e4e
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2207139
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>

client/simple_address_range_bag.h

@@ -16,6 +16,7 @@
 #define CRASHPAD_CLIENT_SIMPLE_ADDRESS_RANGE_BAG_H_
 
 #include <stdint.h>
+#include <string.h>
 
 #include <type_traits>
 

snapshot/minidump/minidump_context_converter.cc

@@ -14,6 +14,8 @@
 
 #include "snapshot/minidump/minidump_context_converter.h"
 
+#include <string.h>
+
 #include "base/stl_util.h"
 #include "minidump/minidump_context.h"
 

util/linux/ptrace_client.cc

@@ -16,6 +16,7 @@
 
 #include <errno.h>
 #include <stdio.h>
+#include <string.h>
 
 #include <string>
 

util/net/http_multipart_builder.cc

@@ -14,6 +14,7 @@
 
 #include "util/net/http_multipart_builder.h"
 
+#include <string.h>
 #include <sys/types.h>
 
 #include <utility>

util/net/http_transport_socket.cc

@@ -17,6 +17,7 @@
 #include <fcntl.h>
 #include <netdb.h>
 #include <poll.h>
+#include <string.h>
 #include <sys/socket.h>
 
 #include "base/logging.h"

util/process/process_memory.cc

@@ -14,6 +14,8 @@
 
 #include "util/process/process_memory.h"
 
+#include <string.h>
+
 #include <algorithm>
 
 #include "base/logging.h"

util/stream/log_output_stream.cc

@@ -14,6 +14,8 @@
 
 #include "util/stream/log_output_stream.h"
 
+#include <string.h>
+
 #include <algorithm>
 
 #include "base/logging.h"