libgo: bump major version

PR go/108057

The current version is the same as for the previous GCC release,
but there have been minor changes like new type descriptors that
make it impossible to run Go programs built with the previous GCC
release with the current libgo.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/456976

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-1c5bfd57131b68b91d8400bb017f35d416f7aa7b
+9906861dc86c1733bb304d3d45b1534adb32712c
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/configure

@@ -2608,7 +2608,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 ac_config_headers="$ac_config_headers config.h"
 
 
-libtool_VERSION=21:0:0
+libtool_VERSION=22:0:0
 
 
 # Default to --enable-multilib

libgo/configure.ac

@@ -10,7 +10,7 @@ AC_INIT(package-unused, version-unused,, libgo)
 AC_CONFIG_SRCDIR(Makefile.am)
 AC_CONFIG_HEADER(config.h)
 
-libtool_VERSION=21:0:0
+libtool_VERSION=22:0:0
 AC_SUBST(libtool_VERSION)
 
 AM_ENABLE_MULTILIB(, ..)