re PR go/65570 (cannot find package "runtime/cgo")

	PR go/65570
libgo/Makefile.am: add runtime/cgo to list of standard packages

The runtime/cgo package is treated specially by the go tool.
It needs to know that it is always available for gccgo.

From-SVN: r221673

libgo/Makefile.am

@@ -987,7 +987,7 @@ s-zstdpkglist: Makefile
 	echo 'package main' > zstdpkglist.go.tmp
 	echo "" >> zstdpkglist.go.tmp
 	echo 'var stdpkg = map[string]bool{' >> zstdpkglist.go.tmp
-	echo $(libgo_go_objs) 'unsafe.lo' | sed 's/\.lo /\": true,\n/g' | sed 's/\.lo/\": true,/' | sed 's/-go//' | grep -v _c | sed 's/^/\t\"/' | sort | uniq >> zstdpkglist.go.tmp
+	echo $(libgo_go_objs) 'unsafe.lo' 'runtime/cgo.lo' | sed 's/\.lo /\": true,\n/g' | sed 's/\.lo/\": true,/' | sed 's/-go//' | grep -v _c | sed 's/^/\t\"/' | sort | uniq >> zstdpkglist.go.tmp
 	echo '}' >> zstdpkglist.go.tmp
 	$(SHELL) $(srcdir)/mvifdiff.sh zstdpkglist.go.tmp zstdpkglist.go
 	$(STAMP) $@

libgo/Makefile.in

@@ -4403,7 +4403,7 @@ s-zstdpkglist: Makefile
 	echo 'package main' > zstdpkglist.go.tmp
 	echo "" >> zstdpkglist.go.tmp
 	echo 'var stdpkg = map[string]bool{' >> zstdpkglist.go.tmp
-	echo $(libgo_go_objs) 'unsafe.lo' | sed 's/\.lo /\": true,\n/g' | sed 's/\.lo/\": true,/' | sed 's/-go//' | grep -v _c | sed 's/^/\t\"/' | sort | uniq >> zstdpkglist.go.tmp
+	echo $(libgo_go_objs) 'unsafe.lo' 'runtime/cgo.lo' | sed 's/\.lo /\": true,\n/g' | sed 's/\.lo/\": true,/' | sed 's/-go//' | grep -v _c | sed 's/^/\t\"/' | sort | uniq >> zstdpkglist.go.tmp
 	echo '}' >> zstdpkglist.go.tmp
 	$(SHELL) $(srcdir)/mvifdiff.sh zstdpkglist.go.tmp zstdpkglist.go
 	$(STAMP) $@