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/DebugInfo/inline-debug-info.ll b/llvm/test/DebugInfo/inline-debug-info.ll
index 908093c..7230beb 100644
--- a/llvm/test/DebugInfo/inline-debug-info.ll
+++ b/llvm/test/DebugInfo/inline-debug-info.ll
@@ -153,9 +153,9 @@
 !10 = !DISubprogram(name: "test2", linkageName: "_Z5test2v", line: 11, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 11, file: !5, scope: !6, type: !11, function: i32 ()* @_Z5test2v, variables: !2)
 !11 = !DISubroutineType(types: !12)
 !12 = !{!9}
-!13 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "k", line: 4, arg: 1, scope: !4, file: !6, type: !9)
+!13 = !DILocalVariable(name: "k", line: 4, arg: 1, scope: !4, file: !6, type: !9)
 !14 = !DILocation(line: 4, scope: !4)
-!15 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "k2", line: 5, scope: !4, file: !6, type: !9)
+!15 = !DILocalVariable(name: "k2", line: 5, scope: !4, file: !6, type: !9)
 !16 = !DILocation(line: 5, scope: !4)
 !17 = !DILocation(line: 6, scope: !4)
 !18 = !DILocation(line: 7, scope: !4)
@@ -164,7 +164,7 @@
 !21 = !DILocation(line: 14, scope: !22)
 !22 = distinct !DILexicalBlock(line: 13, column: 0, file: !5, scope: !10)
 !23 = !DILocation(line: 15, scope: !22)
-!24 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "e", line: 16, scope: !10, file: !6, type: !9)
+!24 = !DILocalVariable(name: "e", line: 16, scope: !10, file: !6, type: !9)
 !25 = !DILocation(line: 16, scope: !10)
 !26 = !DILocation(line: 17, scope: !27)
 !27 = distinct !DILexicalBlock(line: 16, column: 0, file: !5, scope: !10)