cmd/release: use %USERPROFILE% instead of %GOPATH% in PATH

CL 104115 added %GOPATH%\bin to the PATH. But GOPATH environment
variable might contain directory list. So, if, for example, GOPATH has
"c:\a;c:\b", then PATH is end up with "c:\a;c:\b\bin" - which is wrong -
user, probably, wants both c:\a\bin and c:\b\bin to be listed in his/her
PATH.

Use %USERPROFILE%\go\bin instead, because USERPROFILE always has
directory.

If user wants to change GOPATH, they would have to adjust their PATH
manually.

Updates golang/go#18583

Change-Id: I634a25ace28776c978faebcfcb2c1750d6d17a0d
Reviewed-on: https://go-review.googlesource.com/c/127777
Reviewed-by: Ron Evans <ron@hybridgroup.com>
Reviewed-by: Mario Arranz <marioarranzr@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/cmd/release/releaselet.go b/cmd/release/releaselet.go
index b058c5d..72f28fc 100644
--- a/cmd/release/releaselet.go
+++ b/cmd/release/releaselet.go
@@ -719,7 +719,7 @@
         Part="last"
         Name="PATH"
         Permanent="no"
-        Value="%GOPATH%\bin" />
+        Value="%USERPROFILE%\go\bin" />
     <RemoveFolder
         Id="GoEnvironmentEntries"
         On="uninstall" />