goInstallTools: fix misleading message about installation location

If GOPATH has multiple elements, the current message that simply
appends 'bin' at the end is misleading.

Tested manually by providing go.toolsGopath with multiple elements.
`go get` installed the binaries in the bin directory of the first

Update golang/vscode-go#368

Change-Id: I4dcc87b9fe22f024fcf3fe8c452243eb66d17a15
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/243282
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/src/goInstallTools.ts b/src/goInstallTools.ts
index 6695123..ac33415 100644
--- a/src/goInstallTools.ts
+++ b/src/goInstallTools.ts
@@ -112,7 +112,8 @@
 	if (envForTools['GOBIN']) {
 		installingMsg += `the configured GOBIN: ${envForTools['GOBIN']}`;
 	} else {
-		installingMsg += `${toolsGopath}${path.sep}bin`;
+		const p = toolsGopath.split(path.delimiter).map((e) => path.join(e, 'bin')).join(path.delimiter);
+		installingMsg += `${p}`;
 	// If the user is on Go >= 1.11, tools should be installed with modules enabled.