wsi: Moved definition of CreateXxxSurface extension to CMakefile

Removed component-specific definitions
diff --git a/loader/loader.h b/loader/loader.h
index 18766ef..0c70f59 100644
--- a/loader/loader.h
+++ b/loader/loader.h
@@ -32,14 +32,6 @@
 #ifndef LOADER_H
 #define LOADER_H
 
-#if defined _WIN32
-#define VK_USE_PLATFORM_WIN32_KHR
-#else
-//#define VK_USE_PLATFORM_MIR_KHR
-//#define VK_USE_PLATFORM_WAYLAND_KHR
-#define VK_USE_PLATFORM_XCB_KHR
-//#define VK_USE_PLATFORM_XLIB_KHR
-#endif
 #include <vulkan/vulkan.h>
 #include <vk_loader_platform.h>
 
@@ -193,6 +185,7 @@
 #endif
 #ifdef VK_USE_PLATFORM_XCB_KHR
     PFN_vkGetPhysicalDeviceXcbPresentationSupportKHR GetPhysicalDeviceXcbPresentationSupportKHR;
+    PFN_vkCreateXcbSurfaceKHR vkCreateXcbSurfaceKHR;
 #endif
 #ifdef VK_USE_PLATFORM_XLIB_KHR
     PFN_vkGetPhysicalDeviceXlibPresentationSupportKHR GetPhysicalDeviceXlibPresentationSupportKHR;