Revert "Revert^2 "modprobe: Always log failures to the kernel lo..."

Revert submission 3442704-modprobe-kmsg-sepolicy

Reason for revert: Likely culprit for b/391279588  - verifying through ABTD before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.

Reverted changes: /q/submissionid:3442704-modprobe-kmsg-sepolicy

Change-Id: Ibf0e47c9775de71cdbb9f4b5e4aac8da3acc5d04
diff --git a/toolbox/modprobe.cpp b/toolbox/modprobe.cpp
index fa6297d..13026ac 100644
--- a/toolbox/modprobe.cpp
+++ b/toolbox/modprobe.cpp
@@ -52,7 +52,7 @@
     LOG(INFO) << "  -h, --help: Print this help";
     LOG(INFO) << "  -l, --list: List modules matching pattern";
     LOG(INFO) << "  -r, --remove: Remove MODULE (multiple modules may be specified)";
-    LOG(INFO) << "  -s, --syslog: print to syslog also (deprecated)";
+    LOG(INFO) << "  -s, --syslog: print to syslog also";
     LOG(INFO) << "  -q, --quiet: disable messages";
     LOG(INFO) << "  -v, --verbose: enable more messages, even more with a second -v";
     LOG(INFO);
@@ -76,10 +76,12 @@
     /* NOTREACHED */
 }
 
+auto syslog = false;
+
 void MyLogger(android::base::LogId id, android::base::LogSeverity severity, const char* tag,
               const char* file, unsigned int line, const char* message) {
     android::base::StdioLogger(id, severity, tag, file, line, message);
-    if (message[0]) {
+    if (syslog && message[0]) {
         android::base::KernelLogger(id, severity, tag, file, line, message);
     }
 }
@@ -198,6 +200,7 @@
                 mode = RemoveModulesMode;
                 break;
             case 's':
+                syslog = true;
                 break;
             case 'v':
                 if (android::base::GetMinimumLogSeverity() <= android::base::DEBUG) {