QUIC: fixed bulding perl module by reducing header pollution. The ngx_http_perl_module module doesn't have a notion of including additional search paths through --with-cc-opt, which results in compile error incomplete type 'enum ssl_encryption_level_t' when building nginx without QUIC support. The enum is visible from quic event headers and eventually pollutes ngx_core.h. The fix is to limit including headers to compile units that are real consumers.

--- a/src/core/ngx_core.h
+++ b/src/core/ngx_core.h
@@ -86,8 +86,6 @@ typedef void (*ngx_connection_handler_pt
 #include <ngx_event_openssl.h>
 #if (NGX_OPENSSL_QUIC)
 #include <ngx_event_quic.h>
-#include <ngx_event_quic_transport.h>
-#include <ngx_event_quic_protection.h>
 #endif
 #endif
 #include <ngx_process_cycle.h>