Increase max line length for KatiReader bufio.Scanner

bufio.Scanner defaults to a relatively small max line length of
64kB.  Kati output may have long lines, use a max length of 2MB
instead.

Fixes: 123590367
Test: m checkbuild
Change-Id: Ia869c5c2526621244f0065736e0d5fd9a088df06

ui/status/kati.go

@@ -121,6 +121,7 @@ func KatiReader(st ToolStatus, pipe io.ReadCloser) {
 	}
 
 	scanner := bufio.NewScanner(pipe)
+	scanner.Buffer(nil, 2*1024*1024)
 	for scanner.Scan() {
 		parser.parseLine(scanner.Text())
 	}