DebugInfo: Fix bad debug info for compile units and types

Fix debug info in these tests, which started failing with a WIP patch to
verify compile units and types.  The problems look like they were all
caused by bitrot.  They fell into these categories:

  - Using `!{i32 0}` instead of `!{}`.
  - Using `!{null}` instead of `!{}`.
  - Using `!MDExpression()` instead of `!{}`.
  - Using `!8` instead of `!{!8}`.
  - `file:` references that pointed at `MDCompileUnit`s instead of the
    same `MDFile` as the compile unit.
  - `file:` references that were numerically off-by-one or (off-by-ten).

llvm-svn: 233415
diff --git a/llvm/test/DebugInfo/2010-05-10-MultipleCU.ll b/llvm/test/DebugInfo/2010-05-10-MultipleCU.ll
index 6ccab85..3430e86 100644
--- a/llvm/test/DebugInfo/2010-05-10-MultipleCU.ll
+++ b/llvm/test/DebugInfo/2010-05-10-MultipleCU.ll
@@ -39,6 +39,6 @@
 !14 = !{!15}
 !15 = !MDBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !18 = !MDFile(filename: "a.c", directory: "/tmp/")
-!19 = !{i32 0}
+!19 = !{}
 !20 = !MDFile(filename: "b.c", directory: "/tmp/")
 !21 = !{i32 1, !"Debug Info Version", i32 3}