DebugInfo: Don't include the name of the CU file in the line table file list when it's unneeded

Recommitting r201351 and r201355 (reverted in r201351 and r201355)

We weren't emitting the an empty (header only) line table when the line
table was empty - this made the DWARF invalid (the compile unit would
point to the zero-size debug_lines section where there should've been an
empty line table but there was nothing at all). Fix that, and as a
consequence this works around/addresses PR18809.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201380 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64]Fix the assertion failure caused by "v1i1 SETCC" DAG node.
As v1i1 is illegal, the type legalizer tries to scalarize such node. But if the type operands of SETCC is legal, the scalarization algorithm will cause an assertion failure.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201381 91177308-0d34-0410-b5e6-96231b3b80d8