IR: Make metadata typeless in assembly

Now that `Metadata` is typeless, reflect that in the assembly.  These
are the matching assembly changes for the metadata/value split in
r223802.

  - Only use the `metadata` type when referencing metadata from a call
    intrinsic -- i.e., only when it's used as a `Value`.

  - Stop pretending that `ValueAsMetadata` is wrapped in an `MDNode`
    when referencing it from call intrinsics.

So, assembly like this:

    define @foo(i32 %v) {
      call void @llvm.foo(metadata !{i32 %v}, metadata !0)
      call void @llvm.foo(metadata !{i32 7}, metadata !0)
      call void @llvm.foo(metadata !1, metadata !0)
      call void @llvm.foo(metadata !3, metadata !0)
      call void @llvm.foo(metadata !{metadata !3}, metadata !0)
      ret void, !bar !2
    }
    !0 = metadata !{metadata !2}
    !1 = metadata !{i32* @global}
    !2 = metadata !{metadata !3}
    !3 = metadata !{}

turns into this:

    define @foo(i32 %v) {
      call void @llvm.foo(metadata i32 %v, metadata !0)
      call void @llvm.foo(metadata i32 7, metadata !0)
      call void @llvm.foo(metadata i32* @global, metadata !0)
      call void @llvm.foo(metadata !3, metadata !0)
      call void @llvm.foo(metadata !{!3}, metadata !0)
      ret void, !bar !2
    }
    !0 = !{!2}
    !1 = !{i32* @global}
    !2 = !{!3}
    !3 = !{}

I wrote an upgrade script that handled almost all of the tests in llvm
and many of the tests in cfe (even handling many `CHECK` lines).  I've
attached it (or will attach it in a moment if you're speedy) to PR21532
to help everyone update their out-of-tree testcases.

This is part of PR21532.

llvm-svn: 224257
diff --git a/llvm/test/DebugInfo/array.ll b/llvm/test/DebugInfo/array.ll
index 2c7195b..a9e0510 100644
--- a/llvm/test/DebugInfo/array.ll
+++ b/llvm/test/DebugInfo/array.ll
@@ -6,7 +6,7 @@
   %retval = alloca i32, align 4
   %a = alloca [0 x i32], align 4
   store i32 0, i32* %retval
-  call void @llvm.dbg.declare(metadata !{[0 x i32]* %a}, metadata !6, metadata !{metadata !"0x102"}), !dbg !11
+  call void @llvm.dbg.declare(metadata [0 x i32]* %a, metadata !6, metadata !{!"0x102"}), !dbg !11
   ret i32 0, !dbg !12
 }
 
@@ -15,25 +15,25 @@
 !llvm.dbg.cu = !{!2}
 !llvm.module.flags = !{!16}
 
-!0 = metadata !{metadata !"0x2e\00main\00main\00\003\000\001\000\006\000\000\003", metadata !14, metadata !1, metadata !3, null, i32 ()* @main, null, null, null} ; [ DW_TAG_subprogram ] [line 3] [def] [main]
-!1 = metadata !{metadata !"0x29", metadata !14} ; [ DW_TAG_file_type ]
-!2 = metadata !{metadata !"0x11\0012\00clang version 3.0 (trunk 129138)\000\00\000\00\000", metadata !14, metadata !15, metadata !15, metadata !13, null,  null} ; [ DW_TAG_compile_unit ]
-!3 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", metadata !14, metadata !1, null, metadata !4, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
-!4 = metadata !{metadata !5}
-!5 = metadata !{metadata !"0x24\00int\000\0032\0032\000\000\005", null, metadata !2} ; [ DW_TAG_base_type ]
-!6 = metadata !{metadata !"0x100\00a\004\000", metadata !7, metadata !1, metadata !8} ; [ DW_TAG_auto_variable ]
-!7 = metadata !{metadata !"0xb\003\0012\000", metadata !14, metadata !0} ; [ DW_TAG_lexical_block ]
-!8 = metadata !{metadata !"0x1\00\000\000\0032\000\000", metadata !14, metadata !2, metadata !5, metadata !9, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
-!9 = metadata !{metadata !10}
+!0 = !{!"0x2e\00main\00main\00\003\000\001\000\006\000\000\003", !14, !1, !3, null, i32 ()* @main, null, null, null} ; [ DW_TAG_subprogram ] [line 3] [def] [main]
+!1 = !{!"0x29", !14} ; [ DW_TAG_file_type ]
+!2 = !{!"0x11\0012\00clang version 3.0 (trunk 129138)\000\00\000\00\000", !14, !15, !15, !13, null,  null} ; [ DW_TAG_compile_unit ]
+!3 = !{!"0x15\00\000\000\000\000\000\000", !14, !1, null, !4, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!4 = !{!5}
+!5 = !{!"0x24\00int\000\0032\0032\000\000\005", null, !2} ; [ DW_TAG_base_type ]
+!6 = !{!"0x100\00a\004\000", !7, !1, !8} ; [ DW_TAG_auto_variable ]
+!7 = !{!"0xb\003\0012\000", !14, !0} ; [ DW_TAG_lexical_block ]
+!8 = !{!"0x1\00\000\000\0032\000\000", !14, !2, !5, !9, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
+!9 = !{!10}
 ;CHECK: DW_TAG_subrange_type
 ;CHECK-NEXT: DW_AT_type
 ;CHECK-NOT: DW_AT_lower_bound
 ;CHECK-NOT: DW_AT_upper_bound
 ;CHECK-NEXT: End Of Children Mark
-!10 = metadata !{metadata !"0x21\000\00-1"}        ; [ DW_TAG_subrange_type ]
-!11 = metadata !{i32 4, i32 7, metadata !7, null}
-!12 = metadata !{i32 5, i32 3, metadata !7, null}
-!13 = metadata !{metadata !0}
-!14 = metadata !{metadata !"array.c", metadata !"/private/tmp"}
-!15 = metadata !{i32 0}
-!16 = metadata !{i32 1, metadata !"Debug Info Version", i32 2}
+!10 = !{!"0x21\000\00-1"}        ; [ DW_TAG_subrange_type ]
+!11 = !{i32 4, i32 7, !7, null}
+!12 = !{i32 5, i32 3, !7, null}
+!13 = !{!0}
+!14 = !{!"array.c", !"/private/tmp"}
+!15 = !{i32 0}
+!16 = !{i32 1, !"Debug Info Version", i32 2}