text/template: use sync.OnceValue for builtinFuncs
Replaced sync.Once with sync.OnceValue to simplify code and reduce globals.
Change-Id: I0586df379b855950eacc5b98baad68f6ba0ba129
GitHub-Last-Rev:
7540b1efba864901c1dc00833a72cb9ed306c52f
GitHub-Pull-Request: golang/go#73689
Reviewed-on: https://go-review.googlesource.com/c/go/+/672235
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>