tpm_manager: Unify logging location

This CL defaults tpm_manager daemon logging to syslog.
Logs can be forwarded to stderr by passing the --log_to_stderr switch.
tpm_manager_client now logs to stderr by default.

Bug: 25567627
TEST=Compile and run on DUT

Change-Id: Icd72aa309207eb5dac884bf1ce57209d69288d1d
diff --git a/client/main.cc b/client/main.cc
index 4a1c164..79ae520 100644
--- a/client/main.cc
+++ b/client/main.cc
@@ -327,7 +327,7 @@
 
 int main(int argc, char* argv[]) {
   base::CommandLine::Init(argc, argv);
-  brillo::InitLog(brillo::kLogToSyslog | brillo::kLogToStderr);
+  brillo::InitLog(brillo::kLogToStderr);
   tpm_manager::ClientLoop loop;
   return loop.Run();
 }
diff --git a/server/main.cc b/server/main.cc
index 8a4e74c..dfbe024 100644
--- a/server/main.cc
+++ b/server/main.cc
@@ -104,7 +104,12 @@
 
 int main(int argc, char* argv[]) {
   base::CommandLine::Init(argc, argv);
-  brillo::InitLog(brillo::kLogToSyslog | brillo::kLogToStderr);
+  base::CommandLine *cl = base::CommandLine::ForCurrentProcess();
+  int flags = brillo::kLogToSyslog;
+  if (cl->HasSwitch("log_to_stderr")) {
+    flags |= brillo::kLogToStderr;
+  }
+  brillo::InitLog(flags);
   TpmManagerDaemon daemon;
   LOG(INFO) << "TpmManager Daemon Started.";
   return daemon.Run();