Remove LogSilencer

It's not essencial and for convenience
only, but LogSilencer removed from
protobuf with absl migration.

Author: vitalybuka

examples/libfuzzer/libfuzzer_bin_example.cc

@@ -19,8 +19,6 @@
 #include "port/protobuf.h"
 #include "src/libfuzzer/libfuzzer_macro.h"
 
-protobuf_mutator::protobuf::LogSilencer log_silincer;
-
 template <class Proto>
 using PostProcessor =
     protobuf_mutator::libfuzzer::PostProcessorRegistration<Proto>;

examples/libfuzzer/libfuzzer_example.cc

@@ -19,8 +19,6 @@
 #include "port/protobuf.h"
 #include "src/libfuzzer/libfuzzer_macro.h"
 
-protobuf_mutator::protobuf::LogSilencer log_silincer;
-
 template <class Proto>
 using PostProcessor =
     protobuf_mutator::libfuzzer::PostProcessorRegistration<Proto>;

examples/libxml2/libxml2_example.cc

@@ -20,14 +20,13 @@
 #include "src/libfuzzer/libfuzzer_macro.h"
 
 namespace {
-protobuf_mutator::protobuf::LogSilencer log_silincer;
 void ignore(void* ctx, const char* msg, ...) {}
 
 template <class T, class D>
 std::unique_ptr<T, D> MakeUnique(T* obj, D del) {
   return {obj, del};
 }
-}
+}  // namespace
 
 DEFINE_PROTO_FUZZER(const protobuf_mutator::xml::Input& message) {
   std::string xml = MessageToXml(message.document());

src/utf8_fix_test.cc

@@ -19,8 +19,6 @@
 
 namespace protobuf_mutator {
 
-protobuf::LogSilencer log_silincer;
-
 class FixUtf8StringTest : public ::testing::TestWithParam<int> {
  public:
   bool IsStructurallyValid(const std::string& s) {