Because most of tests assume target-abi=`lp64d`, adding the
corresponding feature is reasonable.
rg -l loongarch -g '!*.s' | xargs sed -i '/mtriple=loongarch/ {/-mattr=/!{/target-abi/! s/mtriple=loongarch.. /&-mattr=+d /}}'
As the LoongArch port is largely modeled after RISCV it has the same
behavior of not accepting `generic` as a CPU name. For better
compatibility with consumers of LLVM (e.g. mesa) follow D121149's suit
and treat `generic` the same as an empty CPU name.
Differential Revision: https://reviews.llvm.org/D134412