misc/ios: pass through SIGCONT in the exec wrapper

Instruct lldb to pass through SIGCONT unhindered when running iOS
tests. Fixes the TestSIGCONT test in os/signal.

For #14318

Change-Id: I669264208cc3d6ecae9fbc8790e0b753a93a5e04
Reviewed-on: https://go-review.googlesource.com/21071Reviewed-by: David Crawshaw <crawshaw@golang.org>

misc/ios/go_darwin_arm_exec.go

@@ -196,6 +196,7 @@ func run(bin string, args []string) (err error) {
 	s.do(`process handle SIGHUP  --stop false --pass true --notify false`)
 	s.do(`process handle SIGPIPE --stop false --pass true --notify false`)
 	s.do(`process handle SIGUSR1 --stop false --pass true --notify false`)
+	s.do(`process handle SIGCONT --stop false --pass true --notify false`)
 	s.do(`process handle SIGSEGV --stop false --pass true --notify false`) // does not work
 	s.do(`process handle SIGBUS  --stop false --pass true --notify false`) // does not work