Fix gcc error for ignoring return value on stack_trace_posix.cc

src/base/debug/stack_trace_posix.cc

Index: src/base/debug/stack_trace_posix.cc
diff --git a/src/base/debug/stack_trace_posix.cc b/src/base/debug/stack_trace_posix.cc
index f2bbdd09b35954c23a048e6bddd37f813996d2ec..cbd722d35cda9e12a33898c912f4da4794148599 100644
--- a/src/base/debug/stack_trace_posix.cc
+++ b/src/base/debug/stack_trace_posix.cc
@@ -175,7 +175,8 @@ void ProcessBacktrace(void* const* trace, size_t size,
 void PrintToStderr(const char* output) {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
   // stack dumping signal handler). NO malloc or stdio is allowed here.
-  write(STDERR_FILENO, output, strlen(output));
+  ssize_t return_val = write(STDERR_FILENO, output, strlen(output));
+  USE(return_val);
 }
 
 void StackDumpSignalHandler(int signal, siginfo_t* info, void* void_context) {