runtime: fix another typo in runtime-gdb.py

tuple, touple,
gdb, gdv,
let's call the whole thing off.

Change-Id: I72d12f6c75061777474e7dec2c90d2a8a3715da6
Reviewed-on: https://go-review.googlesource.com/100836
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/runtime-gdb.py

@@ -455,7 +455,7 @@ def invoke(self, _arg, _from_tty):
 def find_goroutine(goid):
 	"""
 	find_goroutine attempts to find the goroutine identified by goid.
-	It returns a tuple of gdv.Value's representing the stack pointer
+	It returns a tuple of gdb.Value's representing the stack pointer
 	and program counter pointer for the goroutine.
 
 	@param int goid