It is not used by LLVM, but GCC might generates it when compiling
with -fpie, as indicated by PR#40357 .
Besides the regression check, I build a llvm (clang;clang-tools-extra;
compiler-rt;lld) with -fpie and -DLLVM_ENABLE_PIC=OFF with
gcc9 with DLLVM_ENABLE_LLD=ON to check if the
R_AARCH64_LD64_GOTPAGE_LO15 is handled correctly on large
The resulted build generates about 445619
R_AARCH64_LD64_GOTPAGE_LO15 relocations and the resulting
llvm shows no regression on check-all.