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-scopes.ll b/llvm/test/DebugInfo/inline-scopes.ll
index 45324f6..46e08bc 100644
--- a/llvm/test/DebugInfo/inline-scopes.ll
+++ b/llvm/test/DebugInfo/inline-scopes.ll
@@ -111,7 +111,7 @@
 !13 = !{i32 2, !"Dwarf Version", i32 4}
 !14 = !{i32 1, !"Debug Info Version", i32 3}
 !15 = !{!"clang version 3.5.0 "}
-!16 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "b", line: 3, scope: !17, file: !11, type: !18)
+!16 = !DILocalVariable(name: "b", line: 3, scope: !17, file: !11, type: !18)
 !17 = distinct !DILexicalBlock(line: 3, column: 0, file: !1, scope: !12)
 !18 = !DIBasicType(tag: DW_TAG_base_type, name: "bool", size: 8, align: 8, encoding: DW_ATE_boolean)
 !19 = !DILocation(line: 3, scope: !17, inlinedAt: !20)
@@ -119,7 +119,7 @@
 !21 = !DILocation(line: 4, scope: !17, inlinedAt: !20)
 !22 = !DILocation(line: 5, scope: !12, inlinedAt: !20)
 !23 = !DILocation(line: 6, scope: !12, inlinedAt: !20)
-!24 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "b", line: 2, scope: !25, file: !6, type: !18)
+!24 = !DILocalVariable(name: "b", line: 2, scope: !25, file: !6, type: !18)
 !25 = distinct !DILexicalBlock(line: 2, column: 0, file: !5, scope: !26)
 !26 = !DILexicalBlockFile(discriminator: 0, file: !5, scope: !10)
 !27 = !DILocation(line: 2, scope: !25, inlinedAt: !28)