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/Transforms/LoopVectorize/dbg.value.ll b/llvm/test/Transforms/LoopVectorize/dbg.value.ll
index c7440f8..cc1ed8d 100644
--- a/llvm/test/Transforms/LoopVectorize/dbg.value.ll
+++ b/llvm/test/Transforms/LoopVectorize/dbg.value.ll
@@ -53,7 +53,7 @@
 !6 = !{!7}
 !7 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !8 = !{!9}
-!9 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "i", line: 6, scope: !10, file: !4, type: !7)
+!9 = !DILocalVariable(name: "i", line: 6, scope: !10, file: !4, type: !7)
 !10 = distinct !DILexicalBlock(line: 6, column: 0, file: !25, scope: !3)
 !11 = !{!12, !16, !17}
 !12 = !DIGlobalVariable(name: "A", line: 1, isLocal: false, isDefinition: true, scope: null, file: !4, type: !13, variable: [1024 x i32]* @A)