use resource list for socket pooling

Author: Marius Sturm

src/apache20.h

@@ -5,7 +5,7 @@
 #include "apr_lib.h"
 #include "apr_hash.h"
 #include "apr_optional.h"
-#include "apr_atomic.h"
+#include "apr_reslist.h"
 #define APR_WANT_STRFUNC
 #include "apr_want.h"
 #include "apr_tables.h"