BUILD: config: do not include proxy.h nor errors.h anymore in cfgparse.h

These ones induce a long dependency chain and are not needed anymore.
diff --git a/include/haproxy/cfgparse.h b/include/haproxy/cfgparse.h
index 6963522..1c97a88 100644
--- a/include/haproxy/cfgparse.h
+++ b/include/haproxy/cfgparse.h
@@ -23,8 +23,6 @@
 #define _HAPROXY_CFGPARSE_H
 
 #include <haproxy/api.h>
-#include <haproxy/errors.h>
-#include <haproxy/proxy.h>
 
 struct hap_cpuset;
 struct proxy;