test: drop logging suspension

Instead of selectively suspending logging by redirecting messages to
/dev/null, increase the default minimum log severity to FATAL. In the
debug mode, all messages are printed.

test/unit/test.c

@@ -43,6 +43,7 @@ TST_Skip(int line)
 int
 main(int argc, char **argv)
 {
+  LOG_Severity log_severity;
   char *test_name, *s;
   int i, seed = 0;
   struct timeval tv;
@@ -55,9 +56,11 @@ main(int argc, char **argv)
   if (s)
     test_name = s + 1;
 
+  log_severity = LOGS_FATAL;
+
   for (i = 1; i < argc; i++) {
     if (!strcmp(argv[i], "-d")) {
-      LOG_SetMinSeverity(LOGS_DEBUG);
+      log_severity = LOGS_DEBUG;
     } else if (!strcmp(argv[i], "-s") && i + 1 < argc) {
       seed = atoi(argv[++i]);
     } else {
@@ -73,6 +76,7 @@ main(int argc, char **argv)
   fflush(stdout);
 
   LOG_Initialise();
+  LOG_SetMinSeverity(log_severity);
 
   test_unit();
 
@@ -83,16 +87,6 @@ main(int argc, char **argv)
   return 0;
 }
 
-void TST_SuspendLogging(void)
-{
-  LOG_OpenFileLog("/dev/null");
-}
-
-void TST_ResumeLogging(void)
-{
-  LOG_OpenFileLog(NULL);
-}
-
 double
 TST_GetRandomDouble(double min, double max)
 {