[dsymutil] Emit label at the begin of a CU

When emitting a CU, store the MCSymbol pointing to the beginning of the
CU. We'll need this information later when emitting the .debug_names
section (DWARF5 accelerator table).

llvm-svn: 336433
GitOrigin-RevId: 7f19d0160b0723fa72654f2c190903b6a4e48a4c
2 files changed