qapi: Generate QAPIEvent stuff into separate files

Having to include qapi-events.h just for QAPIEvent is suboptimal, but
quite tolerable now.  It'll become problematic when we have events
conditional on the target, because then qapi-events.h won't be usable
from target-independent code anymore.  Avoid that by generating it
into separate files.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190214152251.2073-6-armbru@redhat.com>
diff --git a/Makefile b/Makefile
index 3658310..53d161b 100644
--- a/Makefile
+++ b/Makefile
@@ -101,6 +101,7 @@
 GENERATED_QAPI_FILES += qapi/qapi-commands.h qapi/qapi-commands.c
 GENERATED_QAPI_FILES += $(QAPI_MODULES:%=qapi/qapi-commands-%.h)
 GENERATED_QAPI_FILES += $(QAPI_MODULES:%=qapi/qapi-commands-%.c)
+GENERATED_QAPI_FILES += qapi/qapi-emit-events.h qapi/qapi-emit-events.c
 GENERATED_QAPI_FILES += qapi/qapi-events.h qapi/qapi-events.c
 GENERATED_QAPI_FILES += $(QAPI_MODULES:%=qapi/qapi-events-%.h)
 GENERATED_QAPI_FILES += $(QAPI_MODULES:%=qapi/qapi-events-%.c)