emulators/mame: fix build on powerpc* CURRENT

Use newer LLVM:
Assertion failed: (ESI.Type != EST_Uninstantiated), function SubstExceptionSpec, file /usr/local/poudriere/jails/main-powerpc/usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp, line 2240.