[builder][standalone-build-x86_64] Use ccache to speedup builds and test lld

[kwk]

Summary

ccache was suggested by @nikic in
https://reviews.llvm.org/D134973#3827668.

[nikic]

LGTM

zorg/buildbot/builders/annotated/standalone-build.sh

cmake \
         -DLLVM_BUILD_LLVM_DYLIB=ON \
         -DLLVM_LINK_LLVM_DYLIB=ON \
         -DLLVM_INCLUDE_BENCHMARKS=OFF \
         -DLLVM_INSTALL_UTILS=ON \
         -DCMAKE_INSTALL_PREFIX=${LLVM_INSTALL_DIR} \
         -DLLVM_EXTERNAL_LIT=${PYTHON_LIT_INSTALL_DIR}/usr/local/bin/lit \
         -DLLVM_INCLUDE_UTILS:BOOL=ON \
         -DLLVM_INSTALL_UTILS:BOOL=ON \
-        -DLLVM_UTILS_INSTALL_DIR:PATH=${LLVM_INSTALL_DIR}/bin
+        -DLLVM_UTILS_INSTALL_DIR:PATH=${LLVM_INSTALL_DIR}/bin \
+        -DLLVM_CCACHE_BUILD=ON
 
     build_step "Building llvm"
     cmake --build ${LLVM_BUILD_DIR}
     
     build_step "Testing llvm"
     LD_LIBRARY_PATH="${LLVM_INSTALL_DIR}/lib64" cmake --build ${LLVM_BUILD_DIR} --target check-all
 
     build_step "Installing llvm"
cmake \
         -G Ninja \
         -DCMAKE_BUILD_TYPE=${BUILD_TYPE} \
         -DCLANG_LINK_CLANG_DYLIB=ON \
         -DCLANG_INCLUDE_TESTS=ON \
         -DLLVM_EXTERNAL_LIT=${PYTHON_LIT_INSTALL_DIR}/usr/local/bin/lit \
         -DCMAKE_INSTALL_PREFIX=${CLANG_INSTALL_DIR} \
         -DLLVM_ROOT=${LLVM_INSTALL_DIR} \
         -DLLVM_ENABLE_ASSERTIONS=ON \
-        -DLLVM_TABLEGEN_EXE=${LLVM_INSTALL_DIR}/bin/llvm-tblgen
+        -DLLVM_TABLEGEN_EXE=${LLVM_INSTALL_DIR}/bin/llvm-tblgen \
+        -DLLVM_CCACHE_BUILD=ON
 
     build_step "Building clang"
     LD_LIBRARY_PATH="${LLVM_INSTALL_DIR}/lib64" cmake --build ${CLANG_BUILD_DIR}
 
     build_step "Installing clang"
     rm -rf ${CLANG_INSTALL_DIR}
     cmake --install ${CLANG_BUILD_DIR}
 
build_lld() {
     build_step "Configuring lld"
     cmake \
         -S ${LLVM_ROOT}/lld \
         -B ${LLD_BUILD_DIR} \
         -G Ninja \
         -DCMAKE_BUILD_TYPE=${BUILD_TYPE} \
         -DLLVM_LINK_LLVM_DYLIB=ON \
         -DCMAKE_INSTALL_PREFIX=${LLD_INSTALL_DIR} \
-        -DLLVM_ROOT=${LLVM_INSTALL_DIR}
+        -DLLVM_ROOT=${LLVM_INSTALL_DIR} \
+        -DLLVM_CCACHE_BUILD=ON \
+        -DLLVM_INCLUDE_TESTS=ON \
+        -DLLVM_EXTERNAL_LIT=${PYTHON_LIT_INSTALL_DIR}/usr/local/bin/lit
 
     build_step "Building lld"
     LD_LIBRARY_PATH="${LLVM_INSTALL_DIR}/lib64" cmake --build ${LLD_BUILD_DIR}
 
+    build_step "Testing lld"
+    LD_LIBRARY_PATH="${LLVM_INSTALL_DIR}/lib64" cmake --build ${LLD_BUILD_DIR} --target check-lld
+
     build_step "Installing lld"
     rm -rf ${LLD_INSTALL_DIR}
     cmake --install ${LLD_BUILD_DIR}
 
     build_step "Removing lld build dir"
     rm -rf ${LLD_BUILD_DIR}
 }