test: fix flaky test-vm-sigint-existing-handler
Checklist
-
make -j4 test
(UNIX), orvcbuild test nosign
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines
Affected core subsystem(s)
test
Description of change
Set the SIGUSR2
handler before spawning the child process to make sure the signal is always handled.
(Basically the same as https://github.com/nodejs/node/pull/7854) Fixes: https://github.com/nodejs/node/issues/7981