Fix std::cout/std::cerr static initialization order fiasco.

The benchmark library internals write to std::cout/std::cerr during program
startup. This can cause segfaults when the user doesn't include <iostream> in
the benchmark (which init's the streams). This patch fixes this by emitting
a dynamic initializer in every TU which initializes the streams.

include/benchmark/benchmark_api.h

@@ -214,6 +214,10 @@ void UseCharPointer(char const volatile*);
 // registered benchmark.
 Benchmark* RegisterBenchmarkInternal(Benchmark*);
 
+// Ensure that the standard streams are properly initialized in every TU.
+int InitializeStreams();
+static int stream_init_anchor = InitializeStreams();
+
 } // end namespace internal
 
 

src/benchmark.cc

@@ -1199,6 +1199,11 @@ Benchmark* RegisterBenchmarkInternal(Benchmark* bench) {
     return bench;
 }
 
+int InitializeStreams() {
+    static std::ios_base::Init init;
+    return 0;
+}
+
 } // end namespace internal
 
 void Initialize(int* argc, char** argv) {