propagate error from encodeInstruction() back to ks_asm(). this fixes an issue in #9

llvm/include/llvm/MC/MCCodeEmitter.h

llvm/include/llvm/MC/MCELFStreamer.h

llvm/include/llvm/MC/MCObjectStreamer.h

llvm/include/llvm/MC/MCStreamer.h

llvm/lib/MC/MCAssembler.cpp

llvm/lib/MC/MCELFStreamer.cpp

llvm/lib/MC/MCObjectStreamer.cpp

llvm/lib/MC/MCStreamer.cpp

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

.../lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp

llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp

llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp

llvm/lib/Target/Hexagon/AsmParser/HexagonAsmParser.cpp

.../lib/Target/Hexagon/MCTargetDesc/HexagonMCCodeEmitter.cpp

llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCCodeEmitter.h

llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.h

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h

llvm/lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

llvm/lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.h