games/xray_re-tools: unbreak with clang 9

ld: error: utils/converter/level_mesh.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IceAABB.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IceContainer.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IceHPoint.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IceMatrix4x4.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IcePoint.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/Ice/IceRandom.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_AABBTree.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_BaseModel.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_Collider.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_MeshInterface.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_Model.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_OptimizedTree.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_TreeBuilders.o: unable to find library from dependent library specifier: Opcode.lib
ld: error: utils/converter/opcode/OPC_TreeCollider.o: unable to find library from dependent library specifier: Opcode.lib

Reported by: antoine (via bug 240629 exp-run)
Regressed by: https://reviews.llvm.org/rL360984