[MCDwarf] Generate DWARF v5 .debug_rnglists for assembly files

```
// clang -c -gdwarf-5 a.s -o a.o
.section .init; ret
.text; ret
```

.debug_info contains DW_AT_ranges and llvm-dwarfdump will report
a verification error because .debug_rnglists does not exist (not
implemented).

This patch generates .debug_rnglists for assembly files.
emitListsTableHeaderStart() in DwarfDebug.cpp can be shared with
MCDwarf.cpp. Because CodeGen depends on MC, I move the function to
MCDwarf.cpp

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D75375