Apparently when ARM stops at a GDB breakpoint, it appears to be in
syscall.Syscall.  The "info goroutines" test expected it to be in a
runtime function.  Since this isn't fundamental to the test, simply
tweak the test's regexp to make sure "info goroutines" prints some
running goroutine with an active M, but don't require it to be in any
particular function.

Change-Id: Iba2618b46d3dc49cef62ffb72484b83ea7b0317d
Reviewed-on: https://go-review.googlesource.com/5060Reviewed-by: Dave Cheney <dave@cheney.net>