illegal bytecode on RISC-V

[jan vrany]

Smalltalk/X compiled for riscv64-linux-gnu executes illegal bytecode. producing:

INTERP [debug] (19-11-12 23:01:45): illegal bytecode: 108 (0x6c) at pc 325 (101 118 101 108 32 <-)
INTERP [debug] (19-11-12 23:01:45): illegal bytecode: 108 (0x6c) at pc 282 (116 78 105 108 32 <-)
ProcessorScheduler [warning] (2019-11-12 23:03:13.830): cannot evaluate timedBlock ([] in ToolApplicationModel>>startClock) for dead process: 'ST/X Launcher'
DebugView [info] (2019-11-12 23:03:16.505): ignored error while unwinding: UndefinedObject does not understand: #critical:
DebugView [info] (2019-11-12 23:03:16.510): ignored error while unwinding: UndefinedObject does not understand: #critical:
DebugView [info] (2019-11-12 23:03:16.514): ignored error while unwinding: Non boolean receiver - proceed for truth

This is probaly a symptom of something more fundamental as both embedded and standalone test runner UI is messed up (some widgets are missing, layout seem to be wrong).

[jan vrany]

test case

[jan vrany]

Fixed in stc:

5c2e3c08ce28/stx.stc: RISC-V: #define HAS_SIGNED_CHAR

This fixes nasty bug in interpreter causing jumps to wrong
offsets, sometimes out of bytecode array.