s390x: Implement conditional trap instructions

s390x: Implement conditional trap instructions

This implements various z/Architecture instructions that conditionally
yield a data exception ("trap").  The condition is either based on a
comparison being true ("compare and trap") or on a loaded value being
zero ("load and trap").  These instructions haven't been widely used in
the past, but may now be emitted by newer compilers.  Note that the
resulting signal for a data exception is SIGFPE, not SIGTRAP.  Thus this
patch also adds a new jump kind Ijk_SigFPE.