runtime: fix tab/space inconsistency in runtime-gdb.py

Change-Id: I78c6198eb909e679cf0f776b77dda52211bfd347
Reviewed-on: https://go-review.googlesource.com/45133
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/runtime-gdb.py

@@ -436,7 +436,7 @@ def find_goroutine(goid):
 	for thr in gdb.selected_inferior().threads():
 		if thr.ptid[1] == m['procid']:
 			break
-        else:
+	else:
 		return None, None
 	# Get scheduler state from the G's OS thread state.
 	curthr = gdb.selected_thread()