test: fix test-vm-sigint flakiness
Checklist
-
make -j4 test
(UNIX), orvcbuild test nosign
(Windows) passes -
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.
The test was sometimes crashing in my OS X
box when running the test suite because of SIGUSR2
not being handled.