fix scons validation warning

rsrc/SConscript

@@ -66,7 +66,7 @@ if have_xmllint: # This is separate so that alternate xml validators could be us
 			cmd_line = xmllint_command + (src_name,)
 			print(*cmd_line)
 			p = subprocess.Popen(cmd_line,
-				bufsize=1, stdin=PIPE, stdout=PIPE, stderr=PIPE,
+				stdin=PIPE, stdout=PIPE, stderr=PIPE,
 				cwd=source[0].Dir('.').abspath
 			)
 			out, err = p.communicate()