Make miniglog's InitGoogleLogging argument const.

This is in line with glog.  Also, the argument is unused.  Third try.

Change-Id: I23331ae26089956454d66ab9e93fc04d4b24ed2e

internal/ceres/miniglog/glog/logging.h

diff --git a/internal/ceres/miniglog/glog/logging.h b/internal/ceres/miniglog/glog/logging.h
index 98d2b68..303cd8e 100644
--- a/internal/ceres/miniglog/glog/logging.h
+++ b/internal/ceres/miniglog/glog/logging.h
@@ -152,7 +152,7 @@
 // Global set of log sinks. The actual object is defined in logging.cc.
 extern CERES_EXPORT std::set<LogSink*> log_sinks_global;
 
-inline void InitGoogleLogging(char* argv) {
+inline void InitGoogleLogging(const char* /* argv */) {
   // Do nothing; this is ignored.
 }