runtime: fix newosproc throw message on AIX

A pthread_attr_setstacksize failure was reported as
pthread_attr_getstacksize.

Updates #82244

Change-Id: Ic130b1a286addcf493d89ed6ba1b334ab63f2c58
GitHub-Last-Rev: 7fe8af1be4b4e4c50a65059ad7cb764c76918dd0
GitHub-Pull-Request: golang/go#82248
Reviewed-on: https://go-review.googlesource.com/c/go/+/849805
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>

src/runtime/os_aix.go

diff --git a/src/runtime/os_aix.go b/src/runtime/os_aix.go
index bf78869..ccc57fe 100644
--- a/src/runtime/os_aix.go
+++ b/src/runtime/os_aix.go
@@ -222,7 +222,7 @@
 	}
 
 	if pthread_attr_setstacksize(&attr, threadStackSize) != 0 {
-		throw("pthread_attr_getstacksize")
+		throw("pthread_attr_setstacksize")
 	}
 
 	if pthread_attr_setdetachstate(&attr, _PTHREAD_CREATE_DETACHED) != 0 {