Fix silly bug in previous refactoring.

I extracted the refactoring patch from a larger patch that contained other
changes too, but missed one unintentional change and didn't test enough...

src/backend/access/transam/xlog.c

@@ -9499,7 +9499,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
 				if (readFile < 0)
 				{
 					readFile = XLogFileRead(readSegNo, PANIC,
-											curFileTLI,
+											recoveryTargetTLI,
 											XLOG_FROM_STREAM, false);
 					Assert(readFile >= 0);
 				}