go: install binaries to /usr/lib/go/bin/

- Before this, go and gofmt was installed to /usr/bin, which confuses Go
  as it can not figure out $GOROOT automatically by os.Executable, see
  [1] for details.
  By installing binaries to $GOROOT/bin (GOROOT points to /usr/lib/go),
  go can now figure out its GOROOT.

- Provide symlinks in /usr/bin/go{,fmt}-google to ensure it is there.

- Update alternatives file to point corresponding executables to the
  one installed in $GOROOT.

[1]: golang/go#61921 (comment)

lang-golang/go/autobuild/alternatives

@@ -1,2 +1,2 @@
-alternative /usr/bin/go /usr/bin/go-google 80
-alternative /usr/bin/gofmt /usr/bin/gofmt-google 80
+alternative /usr/bin/go /usr/lib/go/bin/go 80
+alternative /usr/bin/gofmt /usr/lib/go/bin/gofmt 80

lang-golang/go/autobuild/build

@@ -59,9 +59,9 @@ cp -rv "$SRCDIR"/{doc,misc} \
 ln -sv ../../share/go/doc \
     "$PKGDIR/usr/lib/go/doc"
 cp -av "$SRCDIR"/bin \
-    "$PKGDIR/usr"
+    "$PKGDIR/usr/lib/go/"
 cp -av "$SRCDIR"/pkg \
-    "$PKGDIR/usr/lib/go"
+    "$PKGDIR/usr/lib/go/"
 cp -av "$GOROOT/src" \
     "$PKGDIR/usr/lib/go/"
 cp -av "$GOROOT/src/cmd" \
@@ -83,10 +83,6 @@ abinfo "Setting executable bit for sql.go ..."
 find "$PKGDIR" \
     -type f -name sql.go -exec chmod -v -x {} \;
 
-abinfo "Creating a symlink for /usr/lib/go/bin to /usr/bin ..."
-ln -svf ../../bin \
-    "$PKGDIR/usr/lib/go/bin"
-
 abinfo "Installing build scripts ..."
 install -Dvm755 "$SRCDIR"/src/make.bash \
     "$PKGDIR/usr/lib/go/src/make.bash"
@@ -103,17 +99,18 @@ install -Dvm644 "$SRCDIR"/VERSION \
     "$PKGDIR/usr/lib/go/VERSION"
 
 abinfo "Touching all installed files ..."
-find "$PKGDIR"/usr/{lib/go/pkg,bin} \
+find "$PKGDIR"/usr/lib/go/{pkg,bin} \
     -type f -exec touch '{}' +
 
 abinfo "Installing basic Go tools ..."
 install -dvm755 "$PKGDIR"/usr/lib/go/pkg/tool/"${GOOS}"_"$GOARCH"
 install -pvm755 "$SRCDIR"/pkg/tool/"${GOOS}"_"$GOARCH"/* \
    "$PKGDIR"/usr/lib/go/pkg/tool/"${GOOS}"_"$GOARCH"
 
-abinfo "Renaming go and gofmt for alternatives ..."
-mv -v "$PKGDIR"/usr/bin/go{,-google}
-mv -v "$PKGDIR"/usr/bin/gofmt{,-google}
+abinfo "Linking go and gofmt installed in GOROOT to /usr/bin ..."
+mkdir "$PKGDIR"/usr/bin
+ln -sfv ../lib/go/bin/go "$PKGDIR"/usr/bin/go-google
+ln -sfv ../lib/go/bin/gofmt "$PKGDIR"/usr/bin/gofmt-google
 
 abinfo "Preparing to build extra Go tools ..."
 mkdir -pv "$SRCDIR"/go-tools/src/golang.org/x/

lang-golang/go/autobuild/build.stage2

@@ -66,9 +66,9 @@ cp -rv "$SRCDIR"/{doc,misc} \
 ln -sv ../../share/go/doc \
     "$PKGDIR/usr/lib/go/doc"
 cp -av "$SRCDIR"/bin \
-    "$PKGDIR/usr"
+    "$PKGDIR/usr/lib/go/"
 cp -av "$SRCDIR"/pkg \
-    "$PKGDIR/usr/lib/go"
+    "$PKGDIR/usr/lib/go/"
 cp -av "$GOROOT/src" \
     "$PKGDIR/usr/lib/go/"
 cp -av "$GOROOT/src/cmd" \
@@ -90,10 +90,6 @@ abinfo "Setting executable bit for sql.go ..."
 find "$PKGDIR" \
     -type f -name sql.go -exec chmod -v -x {} \;
 
-abinfo "Creating a symlink for /usr/lib/go/bin to /usr/bin ..."
-ln -svf ../../bin \
-    "$PKGDIR/usr/lib/go/bin"
-
 abinfo "Installing build scripts ..."
 install -Dvm755 "$SRCDIR"/src/make.bash \
     "$PKGDIR/usr/lib/go/src/make.bash"
@@ -110,17 +106,18 @@ install -Dvm644 "$SRCDIR"/VERSION \
     "$PKGDIR/usr/lib/go/VERSION"
 
 abinfo "Touching all installed files ..."
-find "$PKGDIR"/usr/{lib/go/pkg,bin} \
+find "$PKGDIR"/usr/lib/go/{pkg,bin} \
     -type f -exec touch '{}' +
 
 abinfo "Installing basic Go tools ..."
 install -dvm755 "$PKGDIR"/usr/lib/go/pkg/tool/"${GOOS}"_"$GOARCH"
 install -pvm755 "$SRCDIR"/pkg/tool/"${GOOS}"_"$GOARCH"/* \
    "$PKGDIR"/usr/lib/go/pkg/tool/"${GOOS}"_"$GOARCH"
 
-abinfo "Renaming go and gofmt for alternatives ..."
-mv -v "$PKGDIR"/usr/bin/go{,-google}
-mv -v "$PKGDIR"/usr/bin/gofmt{,-google}
+abinfo "Linking go and gofmt installed in GOROOT to /usr/bin ..."
+mkdir "$PKGDIR"/usr/bin
+ln -sfv ../lib/go/bin/go "$PKGDIR"/usr/bin/go-google
+ln -sfv ../lib/go/bin/gofmt "$PKGDIR"/usr/bin/gofmt-google
 
 abinfo "Preparing to build extra Go tools ..."
 mkdir -pv "$SRCDIR"/go-tools/src/golang.org/x/