Be more clever when passing default arguments in log statements

Default argument values are taken care of at the call site. If we
switch to a separate overload, all of those call sites won't have to
pass the default values, saving a few instructions each time.

In aggregate, this reduces the size of libjingle_peerconnection_so.so
by 12 kB.

Bug: webrtc:9185
Change-Id: I8c792c7c6e5b230376dd129d16d9ed2541444d88
Reviewed-on: https://webrtc-review.googlesource.com/74440
Reviewed-by: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23112}

rtc_base/logging.h

@@ -121,11 +121,12 @@ class LogSink {
 
 class LogMessage {
  public:
+  LogMessage(const char* file, int line, LoggingSeverity sev);
   LogMessage(const char* file,
              int line,
              LoggingSeverity sev,
-             LogErrorContext err_ctx = ERRCTX_NONE,
-             int err = 0);
+             LogErrorContext err_ctx,
+             int err);
 
 #if defined(WEBRTC_ANDROID)
   LogMessage(const char* file, int line, LoggingSeverity sev, const char* tag);