[fixup]: export symbols explicitly

test cases/unit/26 forcefallback/subprojects/notzlib/meson.build

@@ -4,4 +4,4 @@ notzlib_sources = ['notzlib.c']
 
 notzlib = library('notzlib', notzlib_sources)
 
-zlib_dep = declare_dependency(link_with: notzlib, include_directories: include_directories(['.']), sources: notzlib_sources)
+zlib_dep = declare_dependency(link_with: notzlib, include_directories: include_directories(['.']))

test cases/unit/26 forcefallback/subprojects/notzlib/notzlib.c

@@ -1,3 +1,5 @@
+#include "notzlib.h"
+
 int not_a_zlib_function (void)
 {
   return 42;

test cases/unit/26 forcefallback/subprojects/notzlib/notzlib.h

@@ -1 +1,18 @@
-int not_a_zlib_function (void);
+#pragma once
+
+#if defined _WIN32 || defined __CYGWIN__
+#if defined BUILDING_DLL
+  #define DLL_PUBLIC __declspec(dllexport)
+#else
+  #define DLL_PUBLIC __declspec(dllimport)
+#endif
+#else
+  #if defined __GNUC__
+    #define DLL_PUBLIC __attribute__ ((visibility("default")))
+  #else
+    #pragma message ("Compiler does not support symbol visibility.")
+    #define DLL_PUBLIC
+  #endif
+#endif
+
+int DLL_PUBLIC not_a_zlib_function (void);