emulators/libretro-flycast: fix build on FreeBSD 12

Work around the macros major() and minor() being exposed by sys/types.h.

Approved by:	portmgr (build fix blanket)
PR:		274647

emulators/libretro-flycast/files/patch-core_deps_Vulkan-Headers_include_vulkan_vulkan__structs.hpp

@@ -0,0 +1,18 @@
+--- core/deps/Vulkan-Headers/include/vulkan/vulkan_structs.hpp.orig	2023-11-06 20:05:46 UTC
++++ core/deps/Vulkan-Headers/include/vulkan/vulkan_structs.hpp
+@@ -10,6 +10,15 @@
+
+ #include <cstring>  // strcmp
+
++/* avoid conflict with macros from sys/types.h */
++#ifdef major
++# undef major
++#endif
++
++#ifdef minor
++# undef minor
++#endif
++
+ namespace VULKAN_HPP_NAMESPACE
+ {
+   //===============