tracetool: Add MAINTAINERS info

Update the MAINTAINERS file to reflect the new Python tracetool code.

[Commit description written by Stefan Hajnoczi]

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

MAINTAINERS

@@ -553,6 +553,8 @@ Tracing
 M: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
 S: Maintained
 F: trace/
+F: scripts/tracetool.py
+F: scripts/tracetool/
 F: docs/tracing.txt
 T: git://github.com/stefanha/qemu.git tracing