DI: Remove DW_TAG_arg_variable and DW_TAG_auto_variable

Remove the fake `DW_TAG_auto_variable` and `DW_TAG_arg_variable` tags,
using `DW_TAG_variable` in their place Stop exposing the `tag:` field at
all in the assembly format for `DILocalVariable`.

Most of the testcase updates were generated by the following sed script:

    find test/ -name "*.ll" -o -name "*.mir" |
    xargs grep -l 'DILocalVariable' |
    xargs sed -i '' \
      -e 's/tag: DW_TAG_arg_variable, //' \
      -e 's/tag: DW_TAG_auto_variable, //'

There were only a handful of tests in `test/Assembly` that I needed to
update by hand.

(Note: a follow-up could change `DILocalVariable::DILocalVariable()` to
set the tag to `DW_TAG_formal_parameter` instead of `DW_TAG_variable`
(as appropriate), instead of having that logic magically in the backend
in `DbgVariable`.  I've added a FIXME to that effect.)

llvm-svn: 243774
diff --git a/llvm/test/CodeGen/ARM/2009-10-16-Scope.ll b/llvm/test/CodeGen/ARM/2009-10-16-Scope.ll
index 3f47488..76a43dd 100644
--- a/llvm/test/CodeGen/ARM/2009-10-16-Scope.ll
+++ b/llvm/test/CodeGen/ARM/2009-10-16-Scope.ll
@@ -26,7 +26,7 @@
 !1 = distinct !DILexicalBlock(line: 1, column: 1, file: null, scope: !2)
 !2 = !DISubprogram(name: "bar", linkageName: "bar", line: 4, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: false, scope: !3)
 !3 = !DICompileUnit(language: DW_LANG_C99, producer: "clang 1.1", isOptimized: true, emissionKind: 0, file: !8, retainedTypes: !9)
-!4 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "count_", line: 5, scope: !5, file: !3, type: !6)
+!4 = !DILocalVariable(name: "count_", line: 5, scope: !5, file: !3, type: !6)
 !5 = distinct !DILexicalBlock(line: 1, column: 1, file: null, scope: !1)
 !6 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !7 = !DILocation(line: 6, column: 1, scope: !2)