Replaced strerror() calls with threadsafe strerror_r()

runtime/bin/process_android.cc

Index: runtime/bin/process_android.cc
diff --git a/runtime/bin/process_android.cc b/runtime/bin/process_android.cc
index 49df0c5f31ea67d5a80c0a70abe13df1a341a9a1..30a488b2432d786604f74345f3fa2cb94a5629bf 100644
--- a/runtime/bin/process_android.cc
+++ b/runtime/bin/process_android.cc
@@ -267,7 +267,10 @@ dart::Monitor* ExitCodeHandler::thread_terminate_monitor_ = new dart::Monitor();
 
 
 static void SetChildOsErrorMessage(char** os_error_message) {
-  *os_error_message = strdup(strerror(errno));
+  const int kBufferSize = 1024;
+  char error_message[kBufferSize];
+  strerror_r(errno, error_message, kBufferSize);
+  *os_error_message = strdup(error_message);
 }
 
 
@@ -290,7 +293,9 @@ static void ReportChildError(int exec_control_fd) {
   // In the case of failure in the child process write the errno and
   // the OS error message to the exec control pipe and exit.
   int child_errno = errno;
-  char* os_error_message = strerror(errno);
+  const int kBufferSize = 1024;
+  char os_error_message[kBufferSize];
+  strerror_r(errno, os_error_message, kBufferSize);
   ASSERT(sizeof(child_errno) == sizeof(errno));
   int bytes_written =
       FDUtils::WriteToBlocking(