Work around GCC -Wuninitialized when initializing a span from an uninitialized array in logging.

It's uninitialized on purpose; we'll write into it through the span.

PiperOrigin-RevId: 504318917
Change-Id: I79835f0190253b8b470b3ca404f3979715f2a718

absl/log/internal/log_message.cc

@@ -163,7 +163,8 @@ LogMessage::LogMessageData::LogMessageData(const char* file, int line,
                                            absl::Time timestamp)
     : extra_sinks_only(false),
       manipulated(nullptr),
-      encoded_remaining(encoded_buf) {
+      // This `absl::MakeSpan` silences spurious -Wuninitialized from GCC:
+      encoded_remaining(absl::MakeSpan(encoded_buf)) {
   // Legacy defaults for LOG's ostream:
   manipulated.setf(std::ios_base::showbase | std::ios_base::boolalpha);
   entry.full_filename_ = file;