fix GLES2 build

core/rend/vulkan/vulkan_context.h

@@ -19,6 +19,8 @@
     along with Flycast.  If not, see <https://www.gnu.org/licenses/>.
 */
 #pragma once
+#ifdef USE_VULKAN
+
 #include "vulkan.h"
 #include "vmallocator.h"
 #include "quad.h"
@@ -219,3 +221,5 @@ private:
 #endif
 	static VulkanContext *contextInstance;
 };
+
+#endif // USE_VULKAN

core/wsi/egl.h

@@ -23,6 +23,8 @@
 #include <GLES32/gl2ext.h>
 #ifndef GLES2
 #include "gl32funcs.h"
+#else
+extern "C" void load_gles_symbols();
 #endif
 #include "gl_context.h"