[compiler-rt] Disable interceptor trampoline for SPARC

SPARC jmp requires a delay slot after, and without it will likely result
in a crash. For now, just disable interceptor trampolines on SPARC,
because the specific usecase for them (3 interceptors) does not exist on
SPARC (yet). We can revisit, and carefully implement the support for
SPARC when required.

Reported-by: ro