math/spblas: build with clang, fix build on armv7

Port builds fine with base clang. This avoids the use of binutils,
which fail to link the port on armv7 due to the use of the -z relro
option (not supported by ld.bfd on armv7, as is -z norelro).

MFH: 2025Q2
(cherry picked from commit c54ab7ee80097b4ab5ec19c4d02af38b7ac43389)