fuzz: Move init_protocol_warning_severity_level() into global_init()

This is needed so llvm_fuzz will see it too.

src/test/fuzz/fuzzing_common.c

@@ -110,6 +110,9 @@ global_init(void)
 
   /* Make BUG() and nonfatal asserts crash */
   tor_set_failed_assertion_callback(abort);
+
+  /* Make protocol warnings handled correctly. */
+  init_protocol_warning_severity_level();
 }
 
 #ifdef LLVM_FUZZ
@@ -152,8 +155,6 @@ main(int argc, char **argv)
     }
   }
 
-  init_protocol_warning_severity_level();
-
   {
     log_severity_list_t s;
     memset(&s, 0, sizeof(s));