These options can't be forced via kernel config — CC_IS_CLANG is a def_bool auto-detected from --version, and LTO_CLANG_FULL requires the clang compiler (the build uses GCC from default stdenv). When generate-config.pl tries to answer 'y' for these options with the GCC toolchain, make config rejects the answer, the question-answering loop diverges, and the builder exits 255 with 'Error in reading or end of file' repeated in the log. Also bumps kernel from linux_7_0 to linux_7_1.