MAINTAINERS: Add include/block/aio.h to block I/O path section

This file is actually the header for async.c and aio-*.c., so add it to
the same section.
Suggested-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1468826387-10473-1-git-send-email-famz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

MAINTAINERS

@@ -1027,6 +1027,7 @@ F: async.c
 F: aio-*.c
 F: block/io.c
 F: migration/block*
+F: include/block/aio.h
 T: git git://github.com/stefanha/qemu.git block
 
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