Sequoia vs SuiteSparse

[Chris Jones]

> 
> I am puzzled as to why SuiteSparse_GraphBLAS drags in clang17 and 
> SuiteSparse_LAGraph drags in both clang16 and clang17 as build 
> dependencies. I don't see anything in the SuiteSparse Portfile showing 
> those dependencies.
> 

See this line

https://github.com/macports/macports-ports/blob/6220707ee57fe3a51e273a950c4dfe4e7018bd01/math/SuiteSparse/Portfile#L128

likely that veto's any Xcode provided clang, and thus you fall back to 
using the MacPorts provided versions, e.g. clang-17

If clang-17 has issues on macOS15 then please open a trac ticket for 
this, if there isn't one already.