README should include Clang 18 as recommended compiler

[knuxyl]

The README should include that clang 19+ and gcc 14+ will probably not build this project. It took me hours to figure this out. I tested clang 18, 19, 20 and gcc 14 and 15. The only compiler that would work for me was clang 18. This may be specific to aarch64 linux, but I doubt it, but could be just a linux issue.

To Reproduce
Steps to reproduce the behavior:

1. Try to build with any other compiler on linux

Desktop (please complete the following information):

• OS: Gentoo
• Version: 6.17.6
• CPU: Rockchip RK3588
• GPU: Mali G610
• GPU driver: Mesa 25.2.6

[klorfmorf]

Tested it on my machine and it fails trying to build with the following configuration:

clang version 21.1.0
Target: x86_64-pc-windows-msvc
Thread model: posix

C:\...\Goemon64Recomp\lib\rt64\src\contrib\mupen64plus-win32-deps\SDL2-2.26.3\include\SDL_endian.h(40,1): error: definition of builtin function '_m_prefetch'
   40 | _m_prefetch(void *__P)
      | ^
1 error generated.