[Cross compile] broken includes if you cross compile

[SupervisedThinking]

There are two commits which broke cross compilation for me when building additional packages for my LibreELEC fork

• https://github.com/libsdl-org/SDL/commit/c30845395257933685c4e348d34ec029121bd181 gives this result https://pastebin.com/6R4VZRQv

• https://github.com/libsdl-org/SDL/commit/6956f4aa1982b66b234026b46f7bb2dd44c67894 ends up with https://pastebin.com/kKKiFaxR

Last known good commit for me is https://github.com/libsdl-org/SDL/commit/403afdb558bd09741dac494207a9bbc78b1701fd - I've reverted both commits & amiberry builds fine again, need run testing too.

[madebr]

This has been fixed in https://github.com/libsdl-org/SDL/commit/799d39a3022415f698cb92f44b872c8513d83249