Fix obsolete comment in GetSnapshotData

Hi all

There's an outdated reference to GetOldestXmin(true, true) in
GetSnapshotData. It hasn't had that call signature for a long while
now. Update the comment to reflect the current signature.

diff --git a/src/backend/storage/ipc/procarray.c
b/src/backend/storage/ipc/procarray.c
index f32881b..4bf0243 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -1556,7 +1556,8 @@ GetMaxSnapshotSubxidCount(void)
* older than this are known not running any more.
* RecentGlobalXmin: the global xmin (oldest TransactionXmin across all
* running transactions, except those running LAZY VACUUM). This is
- * the same computation done by GetOldestXmin(true, true).
+ * the same computation done by
+ * GetOldestXmin(NULL, PROCARRAY_FLAGS_DEFAULT|PROCARRAY_FLAGS_VACUUM)
* RecentGlobalDataXmin: the global xmin for non-catalog tables
* >= RecentGlobalXmin
*

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services