qapi: skip redundant includes

The purpose of this change is to help create a json file containing
common definitions; each bit of generated C code must be emitted
only one time.

A second history global to all QAPISchema instances has been added
to detect when a file is included more than one time and skip these
includes.
It does not act as a stack and the changes made to it by the
__init__ function are propagated back to the caller so it's really
a global state.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/qapi-schema/include-repetition-sub.json b/tests/qapi-schema/include-repetition-sub.json
new file mode 100644
index 0000000000..6bfffdfd55
--- /dev/null
+++ b/tests/qapi-schema/include-repetition-sub.json
@@ -0,0 +1,2 @@
+{ 'include': 'comments.json' }
+{ 'include': 'comments.json' }