compilation fix for WinCE

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47819 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/zlib/gzio.c

@@ -43,6 +43,12 @@ extern void   free   OF((voidpf ptr));
 #define ALLOC(size) malloc(size)
 #define TRYFREE(p) {if (p) free(p);}
 
+/* there is no errno under Windows CE, provide a dummy one to avoid modifying
+   too much code in this file */
+#ifdef _WIN32_WCE
+static int errno;
+#endif
+
 static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
 
 /* gzip flag byte */