misc/ios,runtime/cgo: remove SIGINT handshake for the iOS exec wrapper

Once upon a time, the iOS exec wrapper needed to change the current
working directory for the binary being tested. To allow that, the
runtime raised a SIGINT signal that the wrapper caught, changed the
working directory and resumed the process.

These days, the current working directory is passed from the wrapper
to the runtime through a special entry in the app metadata and the
SIGINT handshake is not necessary anymore.

Remove the signaling from the runtime and the exec harness.

Change-Id: Ia53bcc9e4724d2ca00207e22b91ce80a05271b55
Reviewed-on: https://go-review.googlesource.com/106096
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

misc/ios/go_darwin_arm_exec.go

@@ -259,11 +259,9 @@ func run(bin string, args []string) (err error) {
 	}
 
 	started = true
-
-	s.doCmd("run", "stop reason = signal SIGINT", 20*time.Second)
-
 	startTestsLen := s.out.Len()
-	fmt.Fprintln(s.in, `process continue`)
+
+	s.do("run")
 
 	passed := func(out *buf) bool {
 		// Just to make things fun, lldb sometimes translates \n into \r\n.

src/runtime/cgo/gcc_darwin_arm.c

@@ -140,8 +140,6 @@ init_working_dir()
 		if (chdir(buf) != 0) {
 			fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", buf);
 		}
-		// Notify the test harness that we're correctly set up
-		raise(SIGINT);
 	}
 }
 

src/runtime/cgo/gcc_darwin_arm64.c

@@ -142,8 +142,6 @@ init_working_dir()
 		if (chdir(buf) != 0) {
 			fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", buf);
 		}
-		// Notify the test harness that we're correctly set up
-		raise(SIGINT);
 	}
 }