cmd/internal/objabi,cmd/link/internal/sym: add SDWARFADDR symbol type

Add a new symbol type: SDWARFADDR. This kind of symbol stores content
to be added to the DWARF .debug_addr section (new with DWARF5). At the
moment these symbols are created only in the linker, but it's not hard to
imagine other implementations in which the compiler would create them,
so they are added to both the compiler and linker symbol kind space.

Updates #26379.

Change-Id: I4a82ead0d59fe6028abfd6d6e3fc3df2e28c0ef6
Reviewed-on: https://go-review.googlesource.com/c/go/+/634415
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: thanm

src/cmd/internal/objabi/symkind.go

@@ -70,6 +70,7 @@ const (
 	SDWARFRANGE
 	SDWARFLOC
 	SDWARFLINES
+	SDWARFADDR
 	// Coverage instrumentation counter for libfuzzer.
 	SLIBFUZZER_8BIT_COUNTER
 	// Coverage instrumentation counter, aux variable for cmd/cover

src/cmd/internal/objabi/symkind_string.go

@@ -141,6 +141,7 @@ const (
 	SDWARFRANGE
 	SDWARFLOC
 	SDWARFLINES
+	SDWARFADDR
 
 	// SEH symbol types
 	SSEHUNWINDINFO
@@ -171,6 +172,7 @@ var AbiSymKindToSymKind = [...]SymKind{
 	objabi.SDWARFRANGE:             SDWARFRANGE,
 	objabi.SDWARFLOC:               SDWARFLOC,
 	objabi.SDWARFLINES:             SDWARFLINES,
+	objabi.SDWARFADDR:              SDWARFADDR,
 	objabi.SLIBFUZZER_8BIT_COUNTER: SLIBFUZZER_8BIT_COUNTER,
 	objabi.SCOVERAGE_COUNTER:       SCOVERAGE_COUNTER,
 	objabi.SCOVERAGE_AUXVAR:        SCOVERAGE_AUXVAR,
@@ -232,5 +234,5 @@ func (t SymKind) IsNOPTRDATA() bool {
 }
 
 func (t SymKind) IsDWARF() bool {
-	return SDWARFSECT <= t && t <= SDWARFLINES
+	return SDWARFSECT <= t && t <= SDWARFADDR
 }