gdb/testsuite: expect SIGSEGV from top GDB spawn id

When testing with the native-extended-gdbserver, I get:

    Thread 1 "xgdb" received signal SIGSEGV, Segmentation fault.
    0x00007ffff6d828f2 in GC_find_limit_with_bound () from /usr/lib/x86_64-linux-gnu/libgc.so.1
    (gdb) FAIL: gdb.gdb/selftest.exp: xgdb is at prompt

This is because the -re that is supposed to match this SIGSEGV is after
`-i $inferior_spawn_id`.  On native, the top and bottom GDB are on the
same spawn id, so it ends up working.  But with a gdbserver board,
that's not the case.  Move the SIGSEGV -re before the `-i
$inferior_spawn_id` line, such that it matches what the top GDB outputs.

Do the same fix in gdb.gdb/python-helper.exp.

Change-Id: I3291630e218a5a3a6a47805b999ddbc9b968c927
Approved-By: Tom Tromey <tom@tromey.com>

gdb/testsuite/gdb.gdb/python-helper.exp

@@ -86,13 +86,13 @@ proc test_python_helper {} {
     # stop is being detected from the inner GDB, hence the use of -i
     # here.
     gdb_test_multiple "continue" "start inner gdb" {
-	-i "$inferior_spawn_id"
 	-re "received signal SIGSEGV.* in GC_.*$outer_prompt_re" {
 	    # Some versions of the GC used by Guile cause a SEGV
 	    # during stack probing.  Ignore this and carry on.
 	    send_gdb "continue\n"
 	    exp_continue
 	}
+	-i "$inferior_spawn_id"
 	-re "\r\n$gdb_prompt $" {
 	    pass $gdb_test_name
 	}

gdb/testsuite/gdb.gdb/selftest.exp

@@ -74,13 +74,13 @@ proc test_with_self { } {
 			"$gdb_prompt $"]
 	set test "xgdb is at prompt"
 	gdb_test_multiple "continue" $test {
-	    -i "$inferior_spawn_id"
 	    -re "received signal SIGSEGV.* in GC_.*$gdb_prompt" {
 		# Some versions of the GC used by Guile cause a SEGV
 		# during stack probing.  Ignore this and carry on.
 		send_gdb "continue\n"
 		exp_continue
 	    }
+	    -i "$inferior_spawn_id"
 	    -re "$banner" {
 		pass $test
 	    }