Write updated .debug_aranges section after optimizations.

Summary:
Write the .debug_aranges section after optimizations to the output binary.
Each function generates at least one range and at most two (one extra for its cold part).
The writing is done manually because LLVM's implementation is tied to the output of
.debug_info (see EmitGenDwarfInfo and EmitGenDwarfARanges in lib/MC/MCDwarf.cpp),
which we don't want to trigger right now.

(cherry picked from FBD3043108)