cmd/internal/goobj: bump version number

There have a few updates to the Go object file in this cycle (e.g.
FuncInfo format change, some changes in constant values), and it
is not compatible with the old tools. Bump up the version number.

Change-Id: Id176979b139c76ded2c50f2678eb313934326d6f
Reviewed-on: https://go-review.googlesource.com/c/go/+/359483
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/src/cmd/internal/goobj/objfile.go b/src/cmd/internal/goobj/objfile.go
index 4dfea84..9765058 100644
--- a/src/cmd/internal/goobj/objfile.go
+++ b/src/cmd/internal/goobj/objfile.go
@@ -31,7 +31,7 @@
 // New object file format.
 //
 //    Header struct {
-//       Magic       [...]byte   // "\x00go117ld"
+//       Magic       [...]byte   // "\x00go118ld"
 //       Fingerprint [8]byte
 //       Flags       uint32
 //       Offsets     [...]uint32 // byte offset of each block below
@@ -215,7 +215,7 @@
 	Offsets     [NBlk]uint32
 }
 
-const Magic = "\x00go117ld"
+const Magic = "\x00go118ld"
 
 func (h *Header) Write(w *Writer) {
 	w.RawString(h.Magic)