* jit/patcher.h: Added #error if included on s390.

* jit/patcher.h: Added #error if included on s390.
* jit/patcher-common.h: Made declarations visible on s390.
* jit/s390/asmpart.S (asm_patcher_wrapper): removed.
* jit/s390/emit.c (emit_patcher_stubs): removed, (emit_patcher_traps): added.
* jit/s390/codegen.h (PATCHER_LONGBRANCHES_NOPS_SKIP, PATCHER_LONGBRANCHES_NOPS): removed, (PATCHER_CALL_SIZE, PATCHER_NOPS, PATCHER_NOPS_SKIP) adapted to patching via signals.
* jit/s390/codegen.c (codegen_emit, codegen_emit_stub_native): Adapted to paching via signals.
* jit/s390/md.c (md_signal_handler_sigill, md_signal_handler_sigsegv): added support for exceptions_new_hardware_exception returning NULL.
* jit/s390/patcher.c: Adapted to paching via signals.