Lanai: Migrate to the new relocation specifier representation
Use MCSpecifierExpr directly and remove the LanaiMCExpr subclass. Define
MCSpecifierExpr::printImpl to print the relocation specifier in decimal
for llvm-mc -show-inst. The output is not guaranteed to be stable.
Depends on f8e0518120cd2850a7f674322bf428bc7d7d3326
("MC: Adjust -show-inst output for MCExpr")
llvm-project
05a9ad97 - Lanai: Migrate to the new relocation specifier representation
