[fiddler] Forward signals to child process in secwrap

Not doing this was causing signals to be swallowed.

Bug: b/496884373
Change-Id: If3275e47b7ad501ccc92f3b942a2db37c8afc0b5
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/1210076
Auto-Submit: Eric Boren <borenet@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

fiddlek/go/fiddle_secwrap/main.go

diff --git a/fiddlek/go/fiddle_secwrap/main.go b/fiddlek/go/fiddle_secwrap/main.go
index 22909b7..1b0782a 100644
--- a/fiddlek/go/fiddle_secwrap/main.go
+++ b/fiddlek/go/fiddle_secwrap/main.go
@@ -640,7 +640,14 @@
 			}
 		}
 
-		if err := unix.PtraceSyscall(wpid, 0); err != nil {
+		// If the child process received a signal other than SIGTRAP (which
+		// ptrace itself uses to pause the process), forward that signal to
+		// the child process.
+		var signal int
+		if status.Stopped() && status.StopSignal() != unix.SIGTRAP {
+			signal = int(status.StopSignal())
+		}
+		if err := unix.PtraceSyscall(wpid, signal); err != nil && err != unix.ESRCH {
 			fmt.Fprintf(os.Stderr, "failed ptrace: %s\n", err)
 		}
 	}