internal/imports: update stdlib index for 1.14

    $ go run mkstdlib.go

Fixes golang/go#38464.

Change-Id: I97cbd0abf6b9d874739d236429aba8ef271c48ee
Reviewed-on: https://go-review.googlesource.com/c/tools/+/228884
Run-TryBot: Akhil Indurti <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: smasher164

internal/imports/mkstdlib.go

@@ -60,6 +60,7 @@ func main() {
 		mustOpen(api("go1.11.txt")),
 		mustOpen(api("go1.12.txt")),
 		mustOpen(api("go1.13.txt")),
+		mustOpen(api("go1.14.txt")),
 
 		// The API of the syscall/js package needs to be computed explicitly,
 		// because it's not included in the GOROOT/api/go1.*.txt files at this time.