Move GSSAPI includes into its own header

Discussion: https://postgr.es/m/20240708173204.3f3xjilglx5wuzx6@awork3.anarazel.d

Author: danielgustafsson

contrib/sslinfo/sslinfo.c

@@ -19,17 +19,6 @@
 #include "miscadmin.h"
 #include "utils/builtins.h"
 
-/*
- * On Windows, <wincrypt.h> includes a #define for X509_NAME, which breaks our
- * ability to use OpenSSL's version of that symbol if <wincrypt.h> is pulled
- * in after <openssl/ssl.h> ... and, at least on some builds, it is.  We
- * can't reliably fix that by re-ordering #includes, because libpq/libpq-be.h
- * #includes <openssl/ssl.h>.  Instead, just zap the #define again here.
- */
-#ifdef X509_NAME
-#undef X509_NAME
-#endif
-
 PG_MODULE_MAGIC;
 
 static Datum X509_NAME_field_to_text(X509_NAME *name, text *fieldName);

src/include/libpq/be-gssapi-common.h

@@ -16,13 +16,7 @@
 
 #ifdef ENABLE_GSS
 
-#if defined(HAVE_GSSAPI_H)
-#include <gssapi.h>
-#include <gssapi_ext.h>
-#else
-#include <gssapi/gssapi.h>
-#include <gssapi/gssapi_ext.h>
-#endif
+#include "libpq/pg-gssapi.h"
 
 extern void pg_GSS_error(const char *errmsg,
 						 OM_uint32 maj_stat, OM_uint32 min_stat);

src/include/libpq/libpq-be.h

@@ -28,11 +28,7 @@
 #include <netinet/tcp.h>
 
 #ifdef ENABLE_GSS
-#if defined(HAVE_GSSAPI_H)
-#include <gssapi.h>
-#else
-#include <gssapi/gssapi.h>
-#endif							/* HAVE_GSSAPI_H */
+#include "libpq/pg-gssapi.h"
 #endif							/* ENABLE_GSS */
 
 #ifdef ENABLE_SSPI

src/include/libpq/pg-gssapi.h

@@ -0,0 +1,43 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg-gssapi.h
+ *       Definitions for including GSSAPI headers
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/libpq/pg-gssapi.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef PG_GSSAPI_H
+#define PG_GSSAPI_H
+
+#ifdef ENABLE_GSS
+
+/* IWYU pragma: begin_exports */
+#if defined(HAVE_GSSAPI_H)
+#include <gssapi.h>
+#include <gssapi_ext.h>
+#else
+#include <gssapi/gssapi.h>
+#include <gssapi/gssapi_ext.h>
+#endif
+/* IWYU pragma: end_exports */
+
+/*
+* On Windows, <wincrypt.h> includes a #define for X509_NAME, which breaks our
+* ability to use OpenSSL's version of that symbol if <wincrypt.h> is pulled
+* in after <openssl/ssl.h> ... and, at least on some builds, it is.  We
+* can't reliably fix that by re-ordering #includes, because libpq/libpq-be.h
+* #includes <openssl/ssl.h>.  Instead, just zap the #define again here.
+*/
+#ifdef X509_NAME
+#undef X509_NAME
+#endif
+
+#endif							/* ENABLE_GSS */
+
+#endif							/* PG_GSSAPI_H */
+

src/interfaces/libpq/libpq-int.h

@@ -44,15 +44,9 @@
 #include "fe-auth-sasl.h"
 #include "pqexpbuffer.h"
 
-/* IWYU pragma: begin_exports */
 #ifdef ENABLE_GSS
-#if defined(HAVE_GSSAPI_H)
-#include <gssapi.h>
-#else
-#include <gssapi/gssapi.h>
-#endif
+#include "libpq/pg-gssapi.h"
 #endif
-/* IWYU pragma: end_exports */
 
 #ifdef ENABLE_SSPI
 #define SECURITY_WIN32