internal/lsp: set env to os.Environ to start

Change-Id: Ia3952f76918957eba46f8ba2c616f14f424ff4b3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179221
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/cache/session.go

diff --git a/internal/lsp/cache/session.go b/internal/lsp/cache/session.go
index 2109153..aa4ea32 100644
--- a/internal/lsp/cache/session.go
+++ b/internal/lsp/cache/session.go
@@ -7,6 +7,7 @@
 import (
 	"context"
 	"fmt"
+	"os"
 	"strings"
 	"sync"
 
@@ -56,6 +57,7 @@
 		backgroundCtx:  backgroundCtx,
 		cancel:         cancel,
 		name:           name,
+		env:            os.Environ(),
 		folder:         folder,
 		filesByURI:     make(map[span.URI]viewFile),
 		filesByBase:    make(map[string][]viewFile),