[jdk17u] RFR: 8274293: Build failure on macOS with Xcode 13.0 as vfork is deprecated

[xpbob]

On Tue, 12 Oct 2021 03:53:06 GMT, xpbob <duke at openjdk.java.net> wrote:

> Backport 252aaa9249d8979366b37d59487b5b039d923e35

tier1 testing finished, no regression

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PR: https://git.openjdk.java.net/jdk17u/pull/183