tools/gen_stage3: explicitly disable LLVM_ENABLE_LTO to fix build error

```
Scanning dependencies of target LLVM
[ 64%] Building CXX object tools/llvm-shlib/CMakeFiles/LLVM.dir/libllvm.cpp.o
[ 64%] Linking CXX shared library ../../lib/libLLVM-14.so
/usr/bin/ld: ../../lib/libLLVMMC.a: member ../../lib/libLLVMMC.a(MCSectionXCOFF.cpp.o) in archive is not an object
collect2: error: ld returned 1 exit status
make[2]: *** [tools/llvm-shlib/CMakeFiles/LLVM.dir/build.make:294: lib/libLLVM-14.so] Error 1
make[1]: *** [CMakeFiles/Makefile2:45218: tools/llvm-shlib/CMakeFiles/LLVM.dir/all] Error 2
make: *** [Makefile:152: all] Error 2
```

tools/gen_stage3.sh

@@ -43,7 +43,7 @@ case "$os" in
         dossh apt install g++ cmake make python3
         dossh cd ${PROJDIR} '&&' git checkout llvmorg-14.0.6
         dossh cd ${PROJDIR} '&&' mkdir -pv build
-        dossh cd ${PROJDIR}/build '&&' cmake ../llvm -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="/root/out" -DCMAKE_INSTALL_PREFIX="/root/out" "'-DLLVM_ENABLE_PROJECTS=lld;clang'" -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_ENABLE_BINDINGS=OFF -DLLVM_ENABLE_LIBXML2=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_INCLUDE_TESTS=OFF -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_BENCHMARKS=OFF -DLLVM_INCLUDE_DOCS=OFF -DLLVM_INCLUDE_GO_TESTS=OFF -DCLANG_BUILD_TOOLS=OFF -DCLANG_INCLUDE_DOCS=OFF
+        dossh cd ${PROJDIR}/build '&&' cmake ../llvm -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="/root/out" -DCMAKE_INSTALL_PREFIX="/root/out" "'-DLLVM_ENABLE_PROJECTS=lld;clang'" -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_ENABLE_LTO=OFF -DLLVM_ENABLE_BINDINGS=OFF -DLLVM_ENABLE_LIBXML2=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_INCLUDE_TESTS=OFF -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_BENCHMARKS=OFF -DLLVM_INCLUDE_DOCS=OFF -DLLVM_INCLUDE_GO_TESTS=OFF -DCLANG_BUILD_TOOLS=OFF -DCLANG_INCLUDE_DOCS=OFF
         dossh cd ${PROJDIR}/build '&&' make install
         dossh shutdown -h now
     ;;