notary/internal/sumweb: extract hasGlobsPathPrefix from glob-matching
notary/internal/sumweb: extract hasGlobsPathPrefix from glob-matching

It will be necessary for GONOPROXY in the go command.
Having a separate function will make it easier to share the code.
(When the code moves into the go command, this function
will probably move to a different package.)

Change-Id: Idac79a40a144068b4cdf9f52f15c66d46f0f2908
Reviewed-on: https://go-review.googlesource.com/c/exp/+/173540
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Filippo Valsorda <4f40cda291c5f9634e1affd3db44947af61f705c@golang.org>

golang/exp,golang/exp,golang/exp