Ensure that startup messages are flushed so they appear in logs immediately.

Author: GrahamDumpleton

docs/release-notes/version-4.5.3.rst

@@ -5,3 +5,8 @@ Version 4.5.3
 Version 4.5.3 of mod_wsgi can be obtained from:
 
   https://codeload.github.com/GrahamDumpleton/mod_wsgi/tar.gz/4.5.3
+
+Bugs Fixed
+----------
+
+1. Ensure that startup messages are flushed so immediately visible in logs.

src/server/__init__.py

@@ -3128,6 +3128,8 @@ def _cmd_setup_server(command, args, options):
 
     print('Locale Setting     :', options['locale'])
 
+    sys.stdout.flush()
+
     if not options['rewrite_rules']:
         options['rewrite_rules'] = options['server_root'] + '/rewrite.conf'