DebugInfo: Emit relocation to debug_line section when emitting asm for asm

I don't think this is reachable by any frontend (why would you transform
asm to asm+debug info?) but it helps tidy up some of this code, avoid
the weird special case of "emit the first CU, store the label, then emit
the rest" in MCDwarfLineTable::Emit by instead having the
DWARF-for-assembly case use the same codepath as DwarfDebug.cpp, by
registering the label of the debug_line section, thus causing it to be
emitted. (with a special case in asm output to just emit the label since
asm output uses the .loc directives, etc, rather than the debug_loc
directly)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205286 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCObjectStreamer.cpp

@@ -383,14 +383,12 @@ void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
 }
 
 void MCObjectStreamer::FinishImpl() {
-  // Dump out the dwarf file & directory tables and line tables.
-  const MCSymbol *LineSectionSymbol = NULL;
-  if (getContext().hasMCLineSections())
-    LineSectionSymbol = MCDwarfLineTable::Emit(this);
-
   // If we are generating dwarf for assembly source files dump out the sections.
   if (getContext().getGenDwarfForAssembly())
-    MCGenDwarfInfo::Emit(this, LineSectionSymbol);
+    MCGenDwarfInfo::Emit(this);
+
+  // Dump out the dwarf file & directory tables and line tables.
+  MCDwarfLineTable::Emit(this);
 
   getAssembler().Finish();
 }