port: avoid warnings with zlib of Conda with CLang

port/cpl_minizip_unzip.h

@@ -64,7 +64,7 @@ extern "C" {
 #endif
 
 #ifndef _ZLIB_H
-#include <zlib.h>
+#include "cpl_zlib_header.h" // to avoid warnings when including zlib.h
 #endif
 
 #ifndef CPL_MINIZIP_IOAPI_H_INCLUDED

port/cpl_minizip_zip.h

@@ -71,7 +71,7 @@ extern "C" {
 #endif
 
 #ifndef _ZLIB_H
-#include "zlib.h"
+#include "cpl_zlib_header.h" // to avoid warnings when including zlib.h
 #endif
 
 #ifndef CPL_MINIZIP_IOAPI_H_INCLUDED

port/cpl_vsil_gzip.cpp

@@ -91,7 +91,7 @@
 #if HAVE_SYS_STAT_H
 #  include <sys/stat.h>
 #endif
-#include <zlib.h>
+#include "cpl_zlib_header.h" // to avoid warnings when including zlib.h
 
 #ifdef HAVE_LIBDEFLATE
 #include "libdeflate.h"

port/cpl_zlib_header.h

@@ -0,0 +1,38 @@
+/******************************************************************************
+ *
+ * Project:  GDAL
+ * Purpose:  Includes zlib header
+ * Author:   Even Rouault <even dot rouault at spatialys dot com>
+ *
+ ******************************************************************************
+ * Copyright (c) 201, Even Rouault <even dot rouault at spatialys dot com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *****************************************************************************/
+
+#ifndef CPL_ZLIB_HEADER_H
+#define CPL_ZLIB_HEADER_H
+
+#if defined(__GNUC__) && !defined(_MSC_VER)
+#pragma GCC system_header
+#endif
+
+#include "zlib.h"
+
+#endif