Increase size of scanner buffer to cope with long line tests

The default buffer size is too small for the long OpSource tests in
VulkanCTS.

VK-GL-CTS: 1050
diff --git a/cherry/testrunner.go b/cherry/testrunner.go
index ec75de3..f7a7ccd 100644
--- a/cherry/testrunner.go
+++ b/cherry/testrunner.go
@@ -844,6 +844,7 @@
 	qpaParser			:= CreateLogContainerParser(qpaParserQueue)
 	countingQpaReader	:= NewCountingReader(qpaReader)
 	scanner				:= bufio.NewScanner(countingQpaReader)
+	scanner.Buffer(nil, 256*1024)
 
 	// Initialize batch result and root group. Add to batch result list.
 	{